Designing a territorialized work system as the making of a milieu.

BACKGROUND: A huge amount of ergonomic research has been carried out in companies. However, territory is now becoming a new frontier for decision-making during design. OBJECTIVE: This article aims to examine how territorial scale impacts the design process of a work system. METHODS: Two types of methods were used. First, we analyzed and defined what constitutes a territorialized work system. On this basis we conducted a design project for the re-conception of a territorialized work system with the linden tree. RESULTS: It is argued that a "territorialized work system" is not limited to its productive dimensions; it engages in a "making of a milieu" which consists of matching the work system with a range of dimensions that make life possible within the territory. CONCLUSION: The territorial aspect of running a design project thus relates to three dimensions: the systemic dimension of the system to be designed, the organization of the design project itself, and the nature of the object to be designed: the possibility of making a milieu, i.e. of being able to live in the territory.

Analyzing the territorial dimensions of work through a comparative study of waste recovery facilities in France and Brazil.

BACKGROUND: Waste production and management from residents and collection for sorting are systems heavily dependent on territorial dimensions. Ergonomic research needs to better integrate such territorial determinants to improve work conditions and design sustainable work systems. OBJECTIVE: Through studies in France and Brazil, this paper analyzes the territorial relations that raise work systems' sustainability challenges for materials recovery facilities (MRFs) and waste management in both countries and examines the links between work activity and territory in MRFs. METHODS: Both studies were based on the principles of activity-oriented ergonomics and used analyses of work activity and sociotechnical systems. The French study focused on interventions conducted over a 42-month period in five MRFs. The Brazilian study was based on a 20-month longitudinal qualitative and quantitative study. RESULTS: In this paper, we argue that territory is a key determining factor in waste production and work. Notably, the consumption patterns of residents and the economic flows within a geographic space determine the waste composition; and the territorially specified public policies, which define technical and social dimensions of waste collection and sorting. However, the territorial dimensions of waste are poorly considered in facility design. Workers' health and sorting system performance are thus affected and negatively compromising plant performance. CONCLUSION: The territory appears as a blind spot in the design of work systems. One of the challenges is to create interfaces and devices that could help to integrate better human activity and waste territorialized anchorage, in a multilevel organization, from local communities to the global recycling chains.

Structuring the simulation for participation during design: Designing integrated operations centers in the oil industry - A case study.

BACKGROUND: The need for participative approaches in design is a key concern for Ergonomics. There exists a vast array of philosophies and techniques which may come under the heading of participation, but several of these methods are indeed not really participatory in the real sense of the concept. OBJECTIVE: The aim of this study is to reveal the elements that allow an ergonomic simulation approach to be applied as a design process method centered on the work perspective and anchored on the participation concept. METHODS: This study is centered on the subsequent analysis of a case study: the design of an Onshore Collaborative Center (OCC), in the context of Integrated Operations (IO) of the oil industry. The simulation sessions were filmed and recorded, and a logbook of the progress of the design process was produced daily in order to preserve the memory of the case. RESULTS: The main result of the research highlights that simulation is a method capable of presenting work as an important factor in the transformation of the project, as well as in technical choices, in addition to opening space for different participants and their various perspectives. However, for it to be an effective method of participation, there is the need for a "back and forth" process between work analysis and simulation during the ergonomic simulation approach. CONCLUSION: This study showed which elements support the construction of ergonomic simulation as a method capable of structuring the participation in design process. For this, the simulation must be based on work analysis and articulate the knowledge of different actors for decision-making to allow for new developments while promoting the vision of work as an important decision variable in the design process.

Designing for unpredictable uses: A case study on cargo handling.

BACKGROUND: Activity ergonomics aims to include work variability into design process to enable various dimensions of use in projects. As design evolves with use, understanding its characteristics is essential to decipher real working requirements. However, situated design can be pluralistic and may lead to different interpretations than initially intended. OBJECTIVE: This paper aims at understanding the relationship between the designing phase of work systems and the situated task design in high uncertainty operations. METHODS: In an ergonomic work analysis, cargo handling operations were observed at offshore platforms, followed by discussions with workers. Two case studies were selected for the intervention process to demonstrate how workers dealt with high uncertainty tasks on site. RESULTS: Situated task design exhibited three main characteristics: (1) the project emerges from the situation; (2) it has an intentional and original character; and (3) it is situated in time and space to solve local problems. CONCLUSIONS: This combination is the essence of a microproject, which is a concept proposed in this paper. The design must provide resources not only to execute work but also to redesign the task on site.

Community Health Agent: a professional world in search of consolidation / Agente comunitário de saúde: um mundo profissional em busca de consolidação

Abstract The contribution of community health agents (CHAs) is strategic for overcoming the biomedical health model. However, weaknesses in defining the specific roles of this profession impose contradictions and impediments to this work, making it difficult to construct the professional world of CHAs. Thus, this study aimed to analyze the tasks performed by the CHAs to reveal the objects, values, and tools, used by these workers to help consolidate their professional world. This study is a qualitative research study guided by the principles of activity ergonomics that include documentary analysis, systematic observations, and interviews. The results showed that due to the myriad of activities performed by the CHAs, the professional world of these workers is not fully delineated. However, it is believed that the results, analysis, and discussion of the data verified in this research, can support the consolidation of the professional world of the CHAs.

Resumo A contribuição do trabalho dos ACS tem sido apontada como estratégica para superação do modelo biomédico de produção de saúde. No entanto, fragilidades na delimitação dessa profissão impõem contradições e impedimentos a esse trabalho, dificultando a construção do mundo profissional dos ACS. Este artigo tem como objetivo analisar as tarefas realizadas pelos ACS no intuito de revelar objeto, valores e ferramentas usadas por esses trabalhadores que ajudem na consolidação do seu mundo profissional. Trata-se de pesquisa qualitativa norteada pelos princípios da Ergonomia da Atividade, que contou com análise documental, observações sistemáticas e entrevistas. Os resultados demonstraram que em virtude de distintas e inúmeras atividades executadas pelos ACS, o mundo profissional desses trabalhadores não está plenamente delineado. Contudo, acredita-se que o resultado, análise e discussão dos dados apurados nesta pesquisa são capazes de apontar elementos que servem para apoiar a consolidação do mundo profissional dos ACS.

The work activity as an interface among different logics: The case of distributing food in a university restaurant.

BACKGROUND: Work activity integrates the tasks to be performed, the means of work available, the instructions, the rules to be observed, the particular factors related to the individuals (skills, inner state), and the effects both on the task and on the operator. By analyzing the activity, the different logics and conflicts in the design of production systems are revealed. OBJECTIVE: To show how the work activity can support the transformation of the working conditions, when revealed by an ergonomic intervention, by integrating the different design standpoints, which are always present in the project's work situations. METHODS: For this case study, the Ergonomic Work Analysis (EWA) was used on the staff that serves meals at a new university restaurant in Rio de Janeiro (Brazil) with a focus on the portioning of the transported ready-cooked meals and the variability related thereto. The results of observations, verbalizations, self-confrontations and strategy analysis, collected through field notes and audio and photographic records, became a final report submitted to the directors of the university restaurant. RESULTS: This research showed that the work activity of the serving maids helped to reveal the different logics of the heterogeneous actors in the design of the work situation under analysis. The work activity, when revealed by an ergonomic intervention, can be an interface during the design process to articulate these different logics and to support the dialog among different design standpoints. Thus, the concept of fixed portioning became a concept of flexible portioning, which provided the serving maids with an increased autonomy level at the counter, thus improving both the quality of services and the working conditions of those involved therewith. CONCLUSIONS: The activity-focused design can be understood as an ongoing, multiple logical process whereby workers bring the design into their workplaces, which reveals aspects of their own activity, thus helping to change the initial concepts. The ergonomic intervention, based on the revealed activity, helps to highlight the existence of different logics and also to support the actors in articulating their own logics during the design process.

Work of community health agents in the Family Health Strategy: meta-synthesis.

OBJECTIVE To systematize and analyze the evidence from qualitative studies that address the perception of Brazilian Community Health Agents about their work. METHODS This is a systematic review of the meta-synthesis type on the work of community health agents, carried out from the Virtual Health Library using the descriptors "Agente Comunitário de Saúde" and "Trabalho", in Portuguese. The strategy was constructed by crossing descriptors, using the Boolean operator "AND", and filtering Brazilian articles, published from 2004 to 2014, which resulted in 129 identified articles. We removed quantitative or quanti-qualitative research articles, essays, debates, literature reviews, reports of experiences, and research that did not include Brazilian Community Health Agents as subjects. Using these criteria, we selected and analyzed 33 studies that allowed us to identify common subjects and differences between them, to group the main conclusions, to classify subjects, and to interpret the content. RESULTS The analysis resulted in three thematic units: characteristics of the work of community health agents, problems related to the work of community health agents, and positive aspects of the work of community health agents. On the characteristics, we could see that the work of the community health agents is permeated by the political and social dimensions of the health work with predominant use of light technologies. The main input is the knowledge that this professional obtains with the contact with families, which is developed with home visits. On the problems in the work of community health agents, we could identify the lack of limits in their attributions, poor conditions, obstacles in the relationship with the community and teams, weak professional training, and bureaucracy. The positive aspects we identified were the recognition of the work by families, resolution, bonding, work with peers, and work close to home. CONCLUSIONS This review provided an overview of the difficulties and positive aspects that are present in the daily work of community health agents. Given this, we have raised two challenges. The first one refers to how public policy makers need to appropriation the research results and the second one refers to the need to invest in studies that are designed to generate solutions for the difficulties faced by community health agents in their work.

Work of community health agents in the family health strategy: meta-synthesis / Trabalho dos agentes comunitários de saúde na estratégia saúde da família: metassíntese

ABSTRACT OBJECTIVE To systematize and analyze the evidence from qualitative studies that address the perception of Brazilian Community Health Agents about their work. METHODS This is a systematic review of the meta-synthesis type on the work of community health agents, carried out from the Virtual Health Library using the descriptors "Agente Comunitário de Saúde" and "Trabalho", in Portuguese. The strategy was constructed by crossing descriptors, using the Boolean operator "AND", and filtering Brazilian articles, published from 2004 to 2014, which resulted in 129 identified articles. We removed quantitative or quanti-qualitative research articles, essays, debates, literature reviews, reports of experiences, and research that did not include Brazilian Community Health Agents as subjects. Using these criteria, we selected and analyzed 33 studies that allowed us to identify common subjects and differences between them, to group the main conclusions, to classify subjects, and to interpret the content. RESULTS The analysis resulted in three thematic units: characteristics of the work of community health agents, problems related to the work of community health agents, and positive aspects of the work of community health agents. On the characteristics, we could see that the work of the community health agents is permeated by the political and social dimensions of the health work with predominant use of light technologies. The main input is the knowledge that this professional obtains with the contact with families, which is developed with home visits. On the problems in the work of community health agents, we could identify the lack of limits in their attributions, poor conditions, obstacles in the relationship with the community and teams, weak professional training, and bureaucracy. The positive aspects we identified were the recognition of the work by families, resolution, bonding, work with peers, and work close to home. CONCLUSIONS This review provided an overview of the difficulties and positive aspects that are present in the daily work of community health agents. Given this, we have raised two challenges. The first one refers to how public policy makers need to appropriation the research results and the second one refers to the need to invest in studies that are designed to generate solutions for the difficulties faced by community health agents in their work.

RESUMO OBJETIVO Sistematizar e analisar evidências levantadas por estudos de natureza qualitativa que abordam a percepção do ACS sobre seu trabalho. MÉTODOS Revisão sistemática, tipo metassíntese, sobre o trabalho dos agentes comunitários de saúde, realizada a partir da Biblioteca Virtual em Saúde utilizando os descritores "Agente Comunitário de Saúde" e "Trabalho". A estratégia foi construída cruzando descritores, usando o operador booleano "AND", e filtrando artigos brasileiros, publicados de 2004 a 2014, resultando em 129 artigos identificados. Foram excluídos artigos de pesquisas quantitativas ou quanti-qualitativas, ensaios, debates, revisões da literatura, relatos de experiências e pesquisas que não incluíram os ACS como sujeitos. Aplicando esses critérios, foram selecionados e analisados 33 estudos que possibilitaram: identificação de temas comuns e diferenças entre eles; agrupamento de principais conclusões; classificação de temas e interpretação de conteúdo. RESULTADOS A análise resultou em três unidades temáticas: Características do trabalho dos agentes comunitários de saúde; Problemas relacionados ao trabalho dos agentes comunitários de saúde; Aspectos positivos do trabalho dos agentes comunitários de saúde. Sobre as características, evidenciou-se que o trabalho dos agentes comunitários de saúde é permeado pelas dimensões política e social do trabalho em saúde com uso predominante de tecnologias leves, tendo como principal insumo o conhecimento que esse profissional obtém junto às famílias, sendo a visita domiciliar o palco para o desenvolvimento desse contato. Sobre os problemas no trabalho dos agentes comunitários de saúde, foram identificados: falta de limites em suas atribuições; condições precárias; obstáculos na relação com a comunidade e equipes; fragilidade na formação profissional e burocratização. Os aspectos positivos identificados foram: reconhecimento do trabalho pelas famílias e resolutividade, formação de vínculo, trabalho junto aos pares e perto da residência. CONCLUSÕES Essa revisão teceu um panorama sobre as dificuldades e aspectos positivos que se apresentam no cotidiano de trabalho dos agentes comunitários de saúde. Frente a isso, levantou dois desafios. O primeiro se refere à necessidade de apropriação dos resultados das pesquisas pelos formuladores de políticas públicas e, o segundo, à necessidade de investimento em estudos que se voltem para engendrar soluções para as dificuldades enfrentadas pelos agentes comunitários de saúde no seu trabalho.

Professional transitions towards sustainable farming systems: The development of farmers' professional worlds.

BACKGROUND: While farming in France and generally in Europe is continuing to intensify, at the expense of its environmental sustainability, promising alternatives are emerging. OBJECTIVE: The processes whereby farmers change and transform their own work, to shift from an intensive mode of production to a self-sufficient and autonomous one, need to be formalized if we are to further our understanding of why and how these forms of sustainable farming activity emerge. METHODS: We use the development of professional worlds theory, a systemic representation of workers' activity, whereby their experience is formalized. This can be explained as the praxis1, conceptual and axiological underpinnings form a system with the object of the action. The development of a professional world is analyzed according to the evolution of its components and the search for pragmatic coherence within it. We analyzed professional transitions towards self-sufficient and autonomous mixed farming through a case study. RESULTS: Our findings showed that the transition is initiated by the discovery of the unthinkable, awareness of a discrepancy between what the farmers think and what they do, the appearance of problems, and the response to external constraints. Professional transition is a non-teleological and non-incremental process; it corresponds to a comparison with reality, and a resolution of difficulties. This process is stimulated by the use of artifacts instrumented by the farmers. CONCLUSION: New perspectives are opened up by this formalization of transitions, in terms of (i) support towards sustainable farming and (ii) the design of sustainable farming systems.

From the past to the future: Integrating work experience into the design process.

BACKGROUND: Integrating work activity issues into design process is a broadly discussed theme in ergonomics. Participation is presented as the main means for such integration. However, a late participation can limit the development of both project solutions and future work activity. OBJECTIVE: This article presents the concept of construction of experience aiming at the articulated development of future activities and project solutions. It is a non-teleological approach where the initial concepts will be transformed by the experience built up throughout the design process. METHODS: The method applied was a case study of an ergonomic participation during the design of a new laboratory complex for biotechnology research. Data was obtained through analysis of records in a simulation process using a Lego scale model and interviews with project participants. RESULTS: The simulation process allowed for developing new ways of working and generating changes in the initial design solutions, which enable workers to adopt their own developed strategies for conducting work more safely and efficiently in the future work system. CONCLUSIONS: Each project decision either opens or closes a window of opportunities for developing a future activity. Construction of experience in a non-teleological design process allows for understanding the consequences of project solutions for future work.

Digital expression profiling of the compartmentalized translatome of Purkinje neurons.

Underlying the complexity of the mammalian brain is its network of neuronal connections, but also the molecular networks of signaling pathways, protein interactions, and regulated gene expression within each individual neuron. The diversity and complexity of the spatially intermingled neurons pose a serious challenge to the identification and quantification of single neuron components. To address this challenge, we present a novel approach for the study of the ribosome-associated transcriptome-the translatome-from selected subcellular domains of specific neurons, and apply it to the Purkinje cells (PCs) in the rat cerebellum. We combined microdissection, translating ribosome affinity purification (TRAP) in nontransgenic animals, and quantitative nanoCAGE sequencing to obtain a snapshot of RNAs bound to cytoplasmic or rough endoplasmic reticulum (rER)-associated ribosomes in the PC and its dendrites. This allowed us to discover novel markers of PCs, to determine structural aspects of genes, to find hitherto uncharacterized transcripts, and to quantify biophysically relevant genes of membrane proteins controlling ion homeostasis and neuronal electrical activities.

BARP suppresses voltage-gated calcium channel activity and Ca2+-evoked exocytosis.

Voltage-gated calcium channels (VGCCs) are key regulators of cell signaling and Ca(2+)-dependent release of neurotransmitters and hormones. Understanding the mechanisms that inactivate VGCCs to prevent intracellular Ca(2+) overload and govern their specific subcellular localization is of critical importance. We report the identification and functional characterization of VGCC ß-anchoring and -regulatory protein (BARP), a previously uncharacterized integral membrane glycoprotein expressed in neuroendocrine cells and neurons. BARP interacts via two cytosolic domains (I and II) with all Cavß subunit isoforms, affecting their subcellular localization and suppressing VGCC activity. Domain I interacts at the α1 interaction domain-binding pocket in Cavß and interferes with the association between Cavß and Cavα1. In the absence of domain I binding, BARP can form a ternary complex with Cavα1 and Cavß via domain II. BARP does not affect cell surface expression of Cavα1 but inhibits Ca(2+) channel activity at the plasma membrane, resulting in the inhibition of Ca(2+)-evoked exocytosis. Thus, BARP can modulate the localization of Cavß and its association with the Cavα1 subunit to negatively regulate VGCC activity.

Novel chloride channel mutations leading to mild myotonia among Chinese.

We describe two Chinese families with a mild form of the myotonia congenita due to novel chloride channel (ClCN1) mutations. In one case, heterozygous I553F and H555N mutations were found. The patient shared the I553F mutation with his healthy father, and his mother had a history of mild myotonia when she was younger. In another family, autosomal dominant myotonia congenita was due to a L844F change. The physiological effects of the mutations were examined by using the two-electrode voltage-clamp technique after expression of the channels in Xenopus oocytes. All mutations drastically shifted the voltage required for half-maximal activation, more under conditions mimicking the homozygous situation, than under conditions mimicking the heterozygous situation. The larger effect was seen in the compound heterozygous situation combining the I553F and the H555N mutations. Our data suggest that myotonia congenita caused by CLCN1 mutations in Chinese have similar variable features to those found in the West.

Nuclear localization of endogenous RGK proteins and modulation of cell shape remodeling by regulated nuclear transport.

The members of the RGK small GTP-binding protein family, Kir/Gem, Rad, Rem and Rem2, are multifunctional proteins that regulate voltage-gated calcium channel activity and cell shape remodeling. Calmodulin (CaM) or CaM 14-3-3 are regulators of RGK functions and their association defines the subcellular localization of RGK proteins. Abolition of CaM association results in the accumulation of RGK proteins in the nucleus, whereas 14-3-3 binding maintains them in the cytoplasm. Kir/Gem possesses nuclear localization signals (NLS) that mediate nuclear accumulation through an importin alpha5-dependent pathway (see Mahalakshmi RN, Nagashima K, Ng MY, Inagaki N, Hunziker W, Béguin P. Nuclear transport of Kir/Gem requires specific signals and importin alpha5 and is regulated by Calmodulin and predicted service phosphorylations. Traffic 2007; doi: 10.1111/j.1600-0854.2007.00598.x). Because the extent of nuclear localization depends on the RGK protein and the cell type, the mechanism and regulation of nuclear transport may differ. Here, we extend our analysis to the other RGK members and show that Rem also binds importin alpha5, whereas Rad associates with importins alpha3, alpha5 and beta through three conserved NLS. Predicted phosphorylation of a serine residue within the bipartite NLS affects, as observed for Kir/Gem, nuclear accumulation of Rem, but not that of Rad or Rem2. We also identify an additional regulatory phosphorylation for all RGK proteins that prevents binding of 14-3-3 and thereby interferes with their cytosolic relocalization by 14-3-3. Functionally, nuclear localization of RGK proteins contributes to the suppression of RGK-mediated cell shape remodeling. Importantly, we show that endogenous RGK proteins are localized predominantly in the nucleus of individual cells of the brain cortex 'in situ' as well as in primary hippocampal cells, indicating that transport between the nucleus and their site of action in the cytoplasm (i.e., cytoskeleton, endoplasmic reticulum or plasma membrane) is of physiological relevance for the regulation of RGK protein function.

Nuclear transport of Kir/Gem requires specific signals and importin alpha5 and is regulated by calmodulin and predicted serine phosphorylations.

Kir/Gem, together with Rad, Rem and Rem2, is a member of the RGK small GTP-binding protein family. These multifunctional proteins regulate voltage-gated calcium channel (VGCC) activity and cell-shape remodeling. Calmodulin and 14-3-3 binding modulate the functions of RGK proteins. Intriguingly, abolishing the binding of calmodulin or calmodulin and 14-3-3 results in nuclear accumulation of RGK proteins. Under certain conditions, the Ca(v)beta3-subunit of VGCCs can be translocated into the nucleus along with the RGK proteins, resulting in channel inactivation. The mechanism by which nuclear localization of RGK proteins is accomplished and regulated, however, is unknown. Here, we identify specific nuclear localization signals (NLS) in Kir/Gem that are both required and sufficient for nuclear transport. Importin alpha5 binds to Kir/Gem, and its depletion using RNA interference impairs nuclear translocation of this RGK protein. Calmodulin and predicted phosphorylations on serine residues within or in the vicinity of a C-terminal bipartite NLS regulate nuclear translocation by interfering with the association between importinalpha5 and Kir/Gem. These predicted phosphorylations, however, do not affect Kir/Gem-mediated calcium channel downregulation but rather, as shown in the accompanying paper (Mahalakshmi RN, Ng MY, Guo K, Qi Z, Hunziker W, Béguin P. Nuclear localization of endogenous RGK proteins and modulation of cell shape remodeling by regulated nuclear transport. Traffic 2007; doi:10.1111/j.1600-0854.2007.00599.x), interfere with cell-shape remodeling.

RGK small GTP-binding proteins interact with the nucleotide kinase domain of Ca2+-channel beta-subunits via an uncommon effector binding domain.

RGK proteins (Kir/Gem, Rad, Rem, and Rem2) form a small subfamily of the Ras superfamily. Despite a conserved GTP binding core domain, several differences suggest that structure, mechanism of action, and functional regulation differ from Ras. RGK proteins down-regulate voltage-gated calcium channel activity by binding in a GTP-dependent fashion to the Cavbeta subunits. Mutational analysis combined with homology modeling reveal a novel effector binding mechanism distinct from that of other Ras GTPases. In this model the Switch 1 region acts as an allosteric activator that facilitates electrostatic interactions between Arg-196 in Kir/Gem and Asp-194, -270, and -272 in the nucleotide-kinase (NK) domain of Cavbeta3 and wedging Val-223 and His-225 of Kir/Gem into a hydrophobic pocket in the NK domain. Kir/Gem interacts with a surface on the NK domain that is distinct from the groove where the voltage-gated calcium channel Cavalpha1 subunit binds. A complex composed of the RGK protein and the Cavbeta3 and Cav1.2 subunits could be revealed in vivo using coimmunoprecipitation experiments. Intriguingly, docking of the RGK protein to the NK domain of the Cavbeta subunit is reminiscent of the binding of GMP to guanylate kinase.

Nuclear sequestration of beta-subunits by Rad and Rem is controlled by 14-3-3 and calmodulin and reveals a novel mechanism for Ca2+ channel regulation.

Voltage-gated Ca2+ channels (VDCCs) are heteromultimeric proteins that mediate Ca2+ influx into cells upon membrane depolarization. These channels are involved in various cellular events, including gene expression, regulation of hormone secretion and synaptic transmission. Kir/Gem, Rad, Rem, and Rem2 belong to the RGK family of Ras-related small G proteins. RGK proteins interact with the beta-subunits and downregulate VDCC activity. Kir/Gem was proposed to prevent surface expression of functional Ca2+ channels, while for Rem2 the mechanism remains controversial. Here, we have analyzed the mechanism by which Rad and Rem regulate VDCC activity. We show that, similar to Kir/Gem and Rem2, 14-3-3 and CaM binding regulate the subcellular distribution of Rad and Rem, which both inhibit Ca2+ channel activity by preventing its expression on the cell surface. This function is regulated by calmodulin and 14-3-3 binding only for Rad and not for Rem. Interestingly, nuclear targeting of Rad and Rem can relocalize and sequester the beta-subunit to the nucleus, thus providing a novel mechanism for Ca2+ channel downregulation.

Roles of 14-3-3 and calmodulin binding in subcellular localization and function of the small G-protein Rem2.

kir/Gem, Rad, Rem and Rem2 comprise the RGK (Rad/Gem/kir) family of Ras-related small G-proteins. Two important functions of RGK proteins are the regulation of the VDCC (voltage-dependent Ca2+ channel) activity and cell-shape remodelling. RGK proteins interact with 14-3-3 and CaM (calmodulin), but their role on RGK protein function is poorly understood. In contrast with the other RGK family members, Rem2 has been reported to bind neither 14-3-3 nor induce membrane extensions. Furthermore, although Rem2 inhibits VDCC activity, it does not prevent cell-surface transport of Ca2+ channels as has been shown for kir/Gem. In the present study, we re-examined the functions of Rem2 and its interaction with 14-3-3 and CaM. We show that Rem2 in fact does interact with 14-3-3 and CaM and induces dendrite-like extensions in COS cells. 14-3-3, together with CaM, regulates the subcellular distribution of Rem2 between the cytoplasm and the nucleus. Rem2 also interacts with the beta-subunits of VDCCs in a GTP-dependent fashion and inhibits Ca2+ channel activity by blocking the alpha-subunit expression at the cell surface. Thus Rem2 shares many previously unrecognized features with the other RGK family members.