RESUMO
The past years have sharpened the industry's understanding of a Quality by Design (QbD) approach toward clinical trials. Using QbD encourages designing quality into a trial during the planning phase. The identification of Critical to Quality (CtQs) factors and specifically Critical Data and Processes (CD&Ps) is key to such a risk-based monitoring approach. A variable that allows monitoring the evolution of risk regarding the CD&Ps is called a Quality Tolerance Limit (QTL) parameter. These parameters are linked to the scientific question(s) of a trial and may identify the issues that can jeopardize the integrity of trial endpoints. This paper focuses on defining what QTL parameters are and providing general guidance on setting thresholds for these parameters allowing for the derivation of an acceptable range of the risk.
Assuntos
Ensaios Clínicos como Assunto , Humanos , Projetos de Pesquisa , Controle de QualidadeRESUMO
ICln is a multifunctional protein involved in regulatory mechanisms as different as membrane ion transport and RNA splicing. The protein is water-soluble, and during regulatory volume decrease after cell swelling, it is able to migrate from the cytosol to the cell membrane. Purified, water-soluble ICln is able to insert into lipid bilayers to form ion channels. Here, we show that ICln159, a truncated ICln mutant, which is also able to form ion channels in lipid bilayers, belongs to the pleckstrin homology (PH) domain superfold family of proteins. The ICln PH domain shows unusual properties as it lacks the electrostatic surface polarization seen in classical PH domains. However, similar to many classical PH domain-containing proteins, ICln interacts with protein kinase C, and in addition, interacts with cAMP-dependent protein kinase and cGMP-dependent protein kinase type II but not cGMP-dependent protein kinase type Ibeta. A major phosphorylation site for all three kinases is Ser-45 within the ICln PH domain. Furthermore, ICln159 interacts with LSm4, a protein involved in splicing and mRNA degradation, suggesting that the ICln159 PH domain may serve as a protein-protein interaction platform.
Assuntos
Proteínas Sanguíneas/química , Canais Iônicos/química , Canais Iônicos/metabolismo , Fosfoproteínas/química , Dobramento de Proteína , Estrutura Terciária de Proteína , Ribonucleoproteínas Nucleares Pequenas/metabolismo , Sequência de Aminoácidos , Animais , Cães , Humanos , Canais Iônicos/genética , Camundongos , Modelos Moleculares , Dados de Sequência Molecular , Células NIH 3T3 , Ressonância Magnética Nuclear Biomolecular , Técnicas de Patch-Clamp , Fosforilação , Proteínas Quinases/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Ribonucleoproteínas Nucleares Pequenas/química , Ribonucleoproteínas Nucleares Pequenas/genéticaRESUMO
The plasma membrane is a highly dynamic cell-barrier if the nature and distribution of its constituents are considered. Ion channels are embedded in these double lipid bilayers, which modulate their 3D-structures. The structure modulations by the lipid bilayer can assume such a degree that channel activation depends on them, as was shown for the KcsA potassium channel. Here we show that the cation-over-anion selectivity of reconstituted ICln channels can be varied by the thickness of a bilayer build of phosphatidylcholines. The shorter the acyl-chains and therefore the thinner the bilayers of the membrane are, the more potassium selective the channels are. In contrast, the longer the acyl-chains and therefore the thicker the membranes are, the more chloride selective the channels become.