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1.
Soft Matter ; 2024 Jul 04.
Artículo en Inglés | MEDLINE | ID: mdl-38963471

RESUMEN

Controlled crystallization, melting and vitrification are important fundamental processes in nature and technology. However, the microscopic details of these fundamental phenomena still lack understanding, in particular how the cooling rate and presence of a wall influence the crystal nucleation and glass formation. Thermoresponsive microgels provide the possibility to study phase transitions at the single-particle level, owing to the ability to tune the particle size with temperature. In this study, we employ composite microgels consisting of a hard core and a crosslinked poly(N-isopropyl acrylamide-co-methacrylic acid) shell to study the crystallization of dense suspensions of soft colloids near a wall using confocal microscopy. We investigate the effect of the cooling rate on the fluid-to-solid transition close to the sample wall. The structures formed during cooling range from glassy in the case of a rapid temperature quench to crystalline when a slow cooling rate is used. Detailed analysis of the final structure reveals that the cooling rate also sets the degree of alignment of the crystal domains with the wall as a result of a balance between homogeneous and heterogeneous crystal nucleation. The results presented here yield valuable insight into the microscopic details of temperature-controlled crystallization near a wall. This understanding will help pave the way towards optimal crystallization conditions for microgel applications.

2.
Pneumologie ; 71(5): 293-296, 2017 May.
Artículo en Alemán | MEDLINE | ID: mdl-28346957

RESUMEN

This paper reports on the case of a 19 year old asylum seeker from Eritrea who presented with hemoptysis, a positive tuberculosis screening (Enzyme Linked Immuno Spot Assay - EliSpot) and mushy faeces submitted with a suspected diagnosis of tuberculosis. Laboratory testing revealed thrombopenia, leukopenia and eosinophilia, while the chest X-ray was inconspicuous. Acid-proof rod bacteria were neither evident in bronchoscopy samples nor in expectorated sputum samples. However, sonographic findings showed a profound splenomegaly, and laboratory testing revealed a Schistosoma mansoni infection. This case demonstrates that in asylum seekers with suspected tuberculosis endemic diseases of the home country need to be considered as alternative diagnoses.


Asunto(s)
Errores Diagnósticos/prevención & control , Hemoptisis/diagnóstico , Hemoptisis/microbiología , Refugiados , Esquistosomiasis mansoni/diagnóstico por imagen , Esquistosomiasis mansoni/microbiología , Tuberculosis/diagnóstico , Animales , Diagnóstico Diferencial , Reacciones Falso Positivas , Hemoptisis/etiología , Humanos , Masculino , Tamizaje Masivo/métodos , Schistosoma mansoni , Esquistosomiasis mansoni/complicaciones , Tuberculosis/complicaciones , Tuberculosis/microbiología , Adulto Joven
3.
Fish Physiol Biochem ; 42(6): 1521-1526, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27178186

RESUMEN

Samples for the analysis of stable isotopes, genetics and other tissue sampling methods of small fish are often taken via lethal techniques. The aim of this study was to determine the suitability of a non-lethal sampling method for removing muscle tissue from fish under 30 cm total length (TL). A 4-mm biopsy punch was used to remove muscle tissue from two different species, Lutjanus russelli (Lutjanidae) and Lethrinus laticaudis (Lethrinidae). Several scales were removed from the sampling location, and then the biopsy punch was inserted to remove the muscle tissue. Immediately following this, a mixture of Fish Bandage™ and three drops of Betadine™ antiseptic solution was applied to the wound to reduce the chance of infection. The biopsy punch removes an average of 8 mg of muscle tissue from the fish, more than is required for stable isotope and genetic analyses (1 mg). The condition of fish subjected to our three treatments, biopsied fish, a handling controls and a tank control, was compared via gill beat counts at the time of biopsy and 3, 6, 9, 12 and 24 h after treatment. Overall, no instances of mortality were recorded across the study for all species and all treatments. This method has been found to be a suitable non-lethal method in the removal of muscle tissue from these two fish species, potentially also other species under 30 cm TL, by eliminating mortality and minimising stress responses in sampled fishes.


Asunto(s)
Músculos/cirugía , Perciformes/cirugía , Animales , Biopsia
4.
Am J Physiol Lung Cell Mol Physiol ; 309(10): L1199-207, 2015 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-26386118

RESUMEN

Here, we tested the hypothesis that a promiscuous bacterial cyclase synthesizes purine and pyrimidine cyclic nucleotides in the pulmonary endothelium. To test this hypothesis, pulmonary endothelial cells were infected with a strain of the Gram-negative bacterium Pseudomonas aeruginosa that introduces only exoenzyme Y (PA103 ΔexoUexoT::Tc pUCPexoY; ExoY(+)) via a type III secretion system. Purine and pyrimidine cyclic nucleotides were simultaneously detected using mass spectrometry. Pulmonary artery (PAECs) and pulmonary microvascular (PMVECs) endothelial cells both possess basal levels of four different cyclic nucleotides in the following rank order: cAMP > cUMP ≈ cGMP ≈ cCMP. Endothelial gap formation was induced in a time-dependent manner following ExoY(+) intoxication. In PAECs, intercellular gaps formed within 2 h and progressively increased in size up to 6 h, when the experiment was terminated. cGMP concentrations increased within 1 h postinfection, whereas cAMP and cUMP concentrations increased within 3 h, and cCMP concentrations increased within 4 h postinfection. In PMVECs, intercellular gaps did not form until 4 h postinfection. Only cGMP and cUMP concentrations increased at 3 and 6 h postinfection, respectively. PAECs generated higher cyclic nucleotide levels than PMVECs, and the cyclic nucleotide levels increased earlier in response to ExoY(+) intoxication. Heterogeneity of the cyclic nucleotide signature in response to P. aeruginosa infection exists between PAECs and PMVECs, suggesting the intracellular milieu in PAECs is more conducive to cNMP generation.


Asunto(s)
Células Endoteliales/metabolismo , Nucleótidos Cíclicos/fisiología , Pseudomonas aeruginosa/enzimología , Permeabilidad Capilar , Células Cultivadas , Células Endoteliales/microbiología , Interacciones Huésped-Patógeno , Microvasos/citología , Arteria Pulmonar/citología
6.
Phys Rev Lett ; 114(5): 054801, 2015 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-25699448

RESUMEN

The Linac Coherent Light Source has added a self-seeding capability to the soft x-ray range using a grating monochromator system. We report the demonstration of soft x-ray self-seeding with a measured resolving power of 2000-5000, wavelength stability of 10(-4), and an increase in peak brightness by a factor of 2-5 across the photon energy range of 500-1000 eV. By avoiding the need for a monochromator at the experimental station, the self-seeded beam can deliver as much as 50-fold higher brightness to users.

7.
Behav Brain Sci ; 37(1): 35-6, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24461251

RESUMEN

Newell & Shanks (N&S) argue against the idea that any significant role for unconscious influences on decision making has been established by research to date. Inasmuch as this conclusion applies to the idea of an "intelligent cognitive unconscious," we would agree. Our concern is that the article could lead the unwary to conclude that there are no unconscious influences on decision making - and never could be. We give reasons why this may not be the case.


Asunto(s)
Toma de Decisiones , Inconsciente en Psicología , Humanos
8.
Nat Genet ; 2(3): 180-5, 1992 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-1345165

RESUMEN

We have performed single pass sequencing of 1,024 human brain cDNAs, over 900 of which seem to represent new human genes. Library prescreening with total brain cDNA significantly reduced repeated sequencing of highly represented cDNAs. A subset of sequenced cDNAs were physically mapped to their chromosomal locations using gene-specific STS primers derived from 3' untranslated regions. We have also determined that human brain cDNAs represent a rich source of gene-associated polymorphic markers. Microsatellite-containing cDNAs can be physically mapped and converted to highly informative genetic markers, thus facilitating integration of the human physical, expression and genetic maps.


Asunto(s)
Química Encefálica/genética , Mapeo Cromosómico , ADN Complementario/genética , Biblioteca de Genes , Análisis de Secuencia de ADN , Secuencia de Bases , Preescolar , Clonación Molecular , ADN Satélite/análisis , Bases de Datos Factuales , Femenino , Feto , Humanos , Lactante , Datos de Secuencia Molecular , Polimorfismo Genético , Proteínas/genética , Secuencias Repetitivas de Ácidos Nucleicos/genética , Análisis de Secuencia de ADN/métodos , Homología de Secuencia de Ácido Nucleico , Atrofias Musculares Espinales de la Infancia/genética
9.
Nat Genet ; 10(4): 415-23, 1995 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-7670491

RESUMEN

Using our data set of 3,143 single pass sequences from human brain cDNA libraries, we have developed a strategy in which gene-based sequence-tagged-sites (STSs), derived from 3'untranslated regions of human cDNAs, are rapidly assigned to megabase-insert yeast artificial chromosomes and somatic cell hybrids to generate regional gene mapping data. Employing this approach, we have mapped 318 cDNAs, representing 308 human genes. Ninety-two of these mapped to regions implicated in human genetic diseases, identifying them as candidate genes. Extension of this strategy has the potential to result in virtually every human gene having, at its 3' end, its own associated STS, with each STS in turn specifying both a corresponding genomic clone and a specific regional location in the genome.


Asunto(s)
Mapeo Cromosómico/métodos , Genoma Humano , Lugares Marcados de Secuencia , Animales , Encéfalo , Cromosomas Artificiales de Levadura , Humanos , Células Híbridas , Reacción en Cadena de la Polimerasa , Roedores
10.
J Environ Manage ; 127: 135-41, 2013 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-23685274

RESUMEN

Results from experiments using an oath to eliminate hypothetical bias in stated preference valuation are presented. An oath has several potential advantages relative to other methods for reducing hypothetical bias. Our empirical results suggest that with an oath, mean hypothetical payments are not different from mean actual payments and that when controlling for experimental participants' characteristics using regression analyses, the oath eliminated hypothetical bias.


Asunto(s)
Ética , Incertidumbre , Humanos , Análisis Multivariante , Análisis de Regresión , Controles Informales de la Sociedad
11.
Learn Environ Res ; : 1-26, 2023 Mar 16.
Artículo en Inglés | MEDLINE | ID: mdl-37360382

RESUMEN

During the COVID-19 pandemic, teachers were forced to move their teaching completely online. While some seized the opportunity to learn and innovate, others experienced difficulties. This study provides insights into the differences between university teachers during the COVID-19 crisis. A survey among university teachers (N = 283) was conducted to investigate their attitudes towards online teaching, beliefs about students' learning, level of stress experienced, self-efficacy and beliefs about their own professional development. Employing a hierarchical cluster analysis, four distinct teacher profiles were found. Profile 1 was critical but eager; Profile 2 was positive but stressed; Profile 3 was critical and reluctant; Profile 4 was optimistic and easy-going. The profiles differed significantly in their use and perception of support. We suggest that teacher education research should carefully consider sampling procedures or take a person-centred research approach and that universities should develop targeted forms of teacher communication, support and policy.

12.
Nat Struct Mol Biol ; 30(11): 1628-1639, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37770717

RESUMEN

To understand how the nucleosome remodeling and deacetylase (NuRD) complex regulates enhancers and enhancer-promoter interactions, we have developed an approach to segment and extract key biophysical parameters from live-cell three-dimensional single-molecule trajectories. Unexpectedly, this has revealed that NuRD binds to chromatin for minutes, decompacts chromatin structure and increases enhancer dynamics. We also uncovered a rare fast-diffusing state of enhancers and found that NuRD restricts the time spent in this state. Hi-C and Cut&Run experiments revealed that NuRD modulates enhancer-promoter interactions in active chromatin, allowing them to contact each other over longer distances. Furthermore, NuRD leads to a marked redistribution of CTCF and, in particular, cohesin. We propose that NuRD promotes a decondensed chromatin environment, where enhancers and promoters can contact each other over longer distances, and where the resetting of enhancer-promoter interactions brought about by the fast decondensed chromatin motions is reduced, leading to more stable, long-lived enhancer-promoter relationships.


Asunto(s)
Cromatina , Nucleosomas , Complejo Desacetilasa y Remodelación del Nucleosoma Mi-2/metabolismo , Regiones Promotoras Genéticas , Elementos de Facilitación Genéticos
13.
J Geophys Res Atmos ; 127(15): e2022JD036597, 2022 Aug 16.
Artículo en Inglés | MEDLINE | ID: mdl-36245641

RESUMEN

Abrupt and large-scale climate changes have occurred repeatedly and within decades during the last glaciation. These events, where dramatic warming occurs over decades, are well represented in both Greenland ice core mineral dust and temperature records, suggesting a causal link. However, the feedbacks between atmospheric dust and climate change during these Dansgaard-Oeschger events are poorly known and the processes driving changes in atmospheric dust emission and transport remain elusive. Constraining dust provenance is key to resolving these gaps. Here, we present a multi-technique analysis of Greenland dust provenance using novel and established, source diagnostic isotopic tracers as well as results from a regional climate model including dust cycle simulations. We show that the existing dominant model for the provenance of Greenland dust as sourced from combined East Asian dust and Pacific volcanics is not supported. Rather, our clay mineralogical and Hf-Sr-Nd and D/H isotopic analyses from last glacial Greenland dust and an extensive range of Northern Hemisphere potential dust sources reveal three most likely scenarios (in order of probability): direct dust sourcing from the Taklimakan Desert in western China, direct sourcing from European glacial sources, or a mix of dust originating from Europe and North Africa. Furthermore, our regional climate modeling demonstrates the plausibility of European or mixed European/North African sources for the first time. We suggest that the origin of dust to Greenland is potentially more complex than previously recognized, demonstrating more uncertainty in our understanding dust climate feedbacks during abrupt events than previously understood.

14.
J Pharmacol Exp Ther ; 339(1): 313-20, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21791628

RESUMEN

N-{[5-(methanesulfonyl)pyridin-2-yl]methyl}-6-methyl-5-(1-methyl-1H-pyrazol-5-yl)-2-oxo-1-[3-(trifluoromethyl)phenyl]-1,2-dihydropyridine-3-carboxamide (AZD9668) is a novel, oral inhibitor of neutrophil elastase (NE), an enzyme implicated in the signs, symptoms, and disease progression in NE-driven respiratory diseases such as bronchiectasis and chronic obstructive pulmonary disease via its role in the inflammatory process, mucus overproduction, and lung tissue damage. In vitro and in vivo experiments were done to evaluate the binding kinetics, potency, and selectivity of AZD9668, its effects in whole-blood and cell-based assays, and its efficacy in models of lung inflammation and damage. In contrast to earlier NE inhibitors, the interaction between AZD9668 and NE was rapidly reversible. AZD9668 was also highly selective for NE over other neutrophil-derived serine proteases. In cell-based assays, AZD9668 inhibited plasma NE activity in zymosan-stimulated whole blood. In isolated human polymorphonuclear cells, AZD9668 inhibited NE activity on the surface of stimulated cells and in the supernatant of primed, stimulated cells. AZD9668 showed good crossover potency to NE from other species. Oral administration of AZD9668 to mice or rats prevented human NE-induced lung injury, measured by lung hemorrhage, and an increase in matrix protein degradation products in bronchoalveolar lavage (BAL) fluid. In an acute smoke model, AZD9668 reduced the inflammatory response to cigarette smoke as indicated by a reduction in BAL neutrophils and interleukin-1ß. Finally, AZD9668 prevented airspace enlargement and small airway wall remodeling in guinea pigs in response to chronic tobacco smoke exposure whether dosed therapeutically or prophylactically. In summary, AZD9668 has the potential to reduce lung inflammation and the associated structural and functional changes in human diseases.


Asunto(s)
Elastasa de Leucocito/antagonistas & inhibidores , Piridonas/farmacología , Inhibidores de Serina Proteinasa , Sulfonas/farmacología , Lesión Pulmonar Aguda/inducido químicamente , Lesión Pulmonar Aguda/tratamiento farmacológico , Animales , Líquido del Lavado Bronquioalveolar/citología , Perros , Relación Dosis-Respuesta a Droga , Enfisema/inducido químicamente , Enfisema/patología , Femenino , Glicina/análogos & derivados , Glicina/farmacología , Cobayas , Humanos , Cinética , Ratones , Ratones Endogámicos BALB C , Oxadiazoles/farmacología , Neumonía/tratamiento farmacológico , Unión Proteica , Pirimidinonas/farmacología , Ratas , Especificidad de la Especie , Especificidad por Sustrato , Sulfonamidas/farmacología , Porcinos , Contaminación por Humo de Tabaco/efectos adversos
16.
Psychol Health Med ; 15(1): 50-60, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20391224

RESUMEN

For nearly 60 years, researchers have examined the relationship between personality traits and exercise participation. Rhodes and Smith (2006), using meta-analytic procedures reported that extraversion, conscientiousness, and neuroticism were significantly related to exercise participation (Personality correlates of physical activity: A review and meta-analysis. British Journal of Sports Medicine, 40, 958-965). Gender as a moderator of the personality and exercise relationship remained inconclusive. In addition, researchers have suggested that the stage approach may lend greater insight as to the importance of personality. The investigator's primary purpose was to determine whether gender moderated the personality and exercise relationship. The secondary purpose was to determine the importance of personality within a stage approach. Participants were 827 females and 657 males college-aged students who completed measures of the "big five" personality traits and two exercise measures. The results indicated that gender was not a moderator and that the stage approach offers insight as hypothesized differences resulted in personality between intentional exercisers and non-exercising individuals as well as within exercising individuals.


Asunto(s)
Ejercicio Físico , Personalidad , Adolescente , Femenino , Humanos , Masculino , Inventario de Personalidad , Factores Sexuales , Adulto Joven
17.
Nat Commun ; 11(1): 5978, 2020 12 08.
Artículo en Inglés | MEDLINE | ID: mdl-33293507

RESUMEN

Many global environmental agendas, including halting biodiversity loss, reversing land degradation, and limiting climate change, depend upon retaining forests with high ecological integrity, yet the scale and degree of forest modification remain poorly quantified and mapped. By integrating data on observed and inferred human pressures and an index of lost connectivity, we generate a globally consistent, continuous index of forest condition as determined by the degree of anthropogenic modification. Globally, only 17.4 million km2 of forest (40.5%) has high landscape-level integrity (mostly found in Canada, Russia, the Amazon, Central Africa, and New Guinea) and only 27% of this area is found in nationally designated protected areas. Of the forest inside protected areas, only 56% has high landscape-level integrity. Ambitious policies that prioritize the retention of forest integrity, especially in the most intact areas, are now urgently needed alongside current efforts aimed at halting deforestation and restoring the integrity of forests globally.


Asunto(s)
Biodiversidad , Conservación de los Recursos Naturales/estadística & datos numéricos , Política Ambiental , Bosques , África Central , Canadá , Cambio Climático , Conservación de los Recursos Naturales/legislación & jurisprudencia , Nueva Guinea , Federación de Rusia
18.
J Cell Biol ; 140(3): 577-90, 1998 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-9456318

RESUMEN

The dynamic vesicle transport processes at the late-Golgi compartment of Saccharomyces cerevisiae (TGN) require dedicated mechanisms for correct localization of resident membrane proteins. In this study, we report the identification of a new gene, GRD19, involved in the localization of the model late-Golgi membrane protein A-ALP (consisting of the cytosolic domain of dipeptidyl aminopeptidase A [DPAP A] fused to the transmembrane and lumenal domains of the alkaline phosphatase [ALP]), which localizes to the yeast TGN. A grd19 null mutation causes rapid mislocalization of the late-Golgi membrane proteins A-ALP and Kex2p to the vacuole. In contrast to previously identified genes involved in late-Golgi membrane protein localization, grd19 mutations cause only minor effects on vacuolar protein sorting. The recycling of the carboxypeptidase Y sorting receptor, Vps10p, between the TGN and the prevacuolar compartment is largely unaffected in grd19Delta cells. Kinetic assays of A-ALP trafficking indicate that GRD19 is involved in the process of retrieval of A-ALP from the prevacuolar compartment. GRD19 encodes a small hydrophilic protein with a predominantly cytosolic distribution. In a yeast mutant that accumulates an exaggerated form of the prevacuolar compartment (vps27), Grd19p was observed to localize to this compartment. Using an in vitro binding assay, Grd19p was found to interact physically with the cytosolic domain of DPAP A. We conclude that Grd19p is a component of the retrieval machinery that functions by direct interaction with the cytosolic tails of certain TGN membrane proteins during the sorting/budding process at the prevacuolar compartment.


Asunto(s)
Proteínas Portadoras/metabolismo , Proteínas Portadoras/fisiología , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/fisiología , Aparato de Golgi/metabolismo , Proteínas de la Membrana/metabolismo , Proproteína Convertasas , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolismo , Vacuolas/metabolismo , Proteínas de Transporte Vesicular , Fosfatasa Alcalina/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Carboxipeptidasas/metabolismo , Proteínas Portadoras/análisis , Proteínas Portadoras/química , Catepsina A , Clonación Molecular , Dipeptidil-Peptidasas y Tripeptidil-Peptidasas/metabolismo , Proteínas Fúngicas/análisis , Proteínas Fúngicas/química , Genes Fúngicos , Membranas Intracelulares/metabolismo , Datos de Secuencia Molecular , Receptores de Superficie Celular/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Saccharomyces cerevisiae/genética , Alineación de Secuencia , Subtilisinas/metabolismo
19.
J Cell Biol ; 129(1): 35-46, 1995 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-7698993

RESUMEN

The Vps1 protein of Saccharomyces cerevisiae is an 80-kD GTPase associated with the Golgi apparatus. Vps1p appears to play a direct role in the retention of late Golgi membrane proteins, which are mislocalized to the vacuolar membrane in its absence. The pathway by which late Golgi and vacuolar membrane proteins reach the vacuole in vps1 delta mutants was investigated by analyzing transport of these proteins in vps1 delta cells that also contained temperature sensitive mutations in either the SEC4 or END4 genes, which are required for a late step in secretion and the internalization step of endocytosis, respectively. Not only was vacuolar transport of a Golgi membrane protein blocked in the vps1 delta sec4-ts and vps1 delta end4-ts double mutant cells at the non-permissive temperature but vacuolar delivery of the vacuolar membrane protein, alkaline phosphatase was also blocked in these cells. Moreover, both proteins expressed in the vps1 delta end4-ts cells at the elevated temperature could be detected on the plasma membrane by a protease digestion assay indicating that these proteins are transported to the vacuole via the plasma membrane in vps1 mutant cells. These data strongly suggest that a loss of Vps1p function causes all membrane traffic departing from the late Golgi normally destined for the prevacuolar compartment to instead be diverted to the plasma membrane. We propose a model in which Vps1p is required for formation of vesicles from the late Golgi apparatus that carry vacuolar and Golgi membrane proteins bound for the prevacuolar compartment.


Asunto(s)
Proteínas Portadoras/genética , Aparato de Golgi/metabolismo , Membranas Intracelulares/metabolismo , Proteínas de la Membrana/metabolismo , Proproteína Convertasas , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolismo , Vacuolas/metabolismo , Secuencia de Aminoácidos , Proteínas Portadoras/metabolismo , Membrana Celular/metabolismo , Proteínas de Unión al GTP/genética , Genotipo , Modelos Biológicos , Datos de Secuencia Molecular , Mutagénesis , Sistemas de Lectura Abierta , Saccharomyces cerevisiae/genética , Subtilisinas/biosíntesis , Subtilisinas/genética , Temperatura , Proteínas de Transporte Vesicular
20.
J Cell Biol ; 104(5): 1183-91, 1987 May.
Artículo en Inglés | MEDLINE | ID: mdl-3032983

RESUMEN

We have constructed a series of mutations in the signal sequence of the yeast vacuolar protein carboxypeptidase Y (CPY), and have used pulse-chase radiolabeling and immunoprecipitation to examine the in vivo effects of these mutations on the entry of the mutant CPY proteins into the secretory pathway. We find that introduction of a negatively charged residue, aspartate, into the hydrophobic core of the signal sequence has no apparent effect on signal sequence function. In contrast, internal in-frame deletions within the signal sequence cause CPY to be synthesized as unglycosylated precursors. These are slowly and inefficiently converted to glycosylated precursors that are indistinguishable from the glycosylated forms produced from the wild-type gene. These precursors are converted to active CPY in a PEP4-dependent manner, indicating that they are correctly localized to the vacuole. Surprisingly, a deletion mutation that removes the entire CPY signal sequence has a similar effect: unglycosylated precursor accumulates in cells carrying this mutant gene, and greater than 10% of it is posttranslationally glycosylated. Thus, the amino-terminal signal sequence of CPY, while important for translocation efficiency, is not absolutely required for the translocation of this protein.


Asunto(s)
Carboxipeptidasas/genética , Señales de Clasificación de Proteína/metabolismo , Saccharomyces cerevisiae/genética , Secuencia de Aminoácidos , Secuencia de Bases , Catepsina A , Deleción Cromosómica , Enzimas de Restricción del ADN , ADN Recombinante/metabolismo , Genes , Genes Fúngicos , Mutación , Plásmidos , Saccharomyces cerevisiae/enzimología , Proteínas de Saccharomyces cerevisiae
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