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Claudin
Claudins are a family of proteins which, along with occludin, are the most important components of the tight junctions ( zonulae occludentes). Tight junctions establish the paracellular barrier that controls the flow of molecules in the intercellular space between the cells of an epithelium. They have four transmembrane domains, with the N-terminus and the C-terminus in the cytoplasm. Structure Claudins are small (20–24/27 kilodalton (kDa)) transmembrane proteins which are found in many organisms, ranging from nematodes to human beings. They all have a very similar structure. Claudins span the cellular membrane 4 times, with the N-terminal end and the C-terminal end both located in the cytoplasm, and two extracellular loops which show the highest degree of conservation. Claudins have both cis and trans interactions between cell membranes. Cis-interactions is when claudins on the same membrane interact, one way they interact is by transmembrane domain having molecular intera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLDN2
Claudin-2 is a protein that in humans is encoded by the ''CLDN2'' gene. It belongs to the group of claudins. Members of the claudin protein family, such as CLDN2, are expressed in an organ-specific manner and regulate the tissue-specific physiologic properties of tight junctions (Sakaguchi et al., 2002). upplied by OMIMref name="entrez" /> Function Claudin-2 is expressed in cation-leaky epithelia such as that of the kidney proximal tubule. Mice that are deficient in claudin-2 have reduced reabsorption of Na+ in the proximal tubule, consistent with a role in paracellular transport Paracellular transport refers to the transfer of substances across an epithelium by passing through the intercellular space ''between'' the cells. It is in contrast to transcellular transport, where the substances travel ''through'' the cell, pass .... Similar results have been obtained with cultured cells, as overexpression in claudin-2 lacking cells leads to increase of permeability for small cati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLDN4
Claudin 4, also known as CLDN4, is a protein which in humans is encoded by the ''CLDN4'' gene. It belongs to the group of claudins. This gene encodes an integral membrane protein, which belongs to the claudin family. The protein is a component of tight junction strands and may play a role in internal organ development and function during pre- and postnatal life. This gene is deleted in Williams-Beuren syndrome, a neurodevelopmental disorder affecting multiple systems. Claudin 4 can also be used as a marker for distinguishing malignant mesothelioma from lung cancer and uterine serous carcinoma. As a pancreatic cancer marker in cell-blocks of effusion specimens, it has also been found to have a superior performance to BerEp4 BerEp4 (also Ber-EP4) is a histologic stain mainly used to aid in the diagnosis of basal cell carcinoma (BCC). It is an antibody to EpCAM (epithelial cell adhesion molecule Epithelial cell adhesion molecule (EpCAM), also known as CD326 among o ... staining ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLDN6
Claudin-6 is a protein that in humans is encoded by the ''CLDN6'' gene. It belongs to the group of claudin Claudins are a family of proteins which, along with occludin, are the most important components of the tight junctions ( zonulae occludentes). Tight junctions establish the paracellular barrier that controls the flow of molecules in the interce ...s. The knockout mice of mouse homolog exhibit no phenotype, indicating that claudin-6 is dispensable for normal development and homeostasis. References External links * Further reading * * * * * * * * * * * * * * * {{gene-16-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLDN7
Claudin-7 is a protein that in humans is encoded by the ''CLDN7'' gene. It belongs to the group of claudin Claudins are a family of proteins which, along with occludin, are the most important components of the tight junctions ( zonulae occludentes). Tight junctions establish the paracellular barrier that controls the flow of molecules in the interce ...s. Claudins, such as CLDN7, are involved in the formation of tight junctions between epithelial cells. Tight junctions restrict lateral diffusion of lipids and membrane proteins, and thereby physically define the border between the apical and basolateral compartments of epithelial cells (Zheng et al., 2003). upplied by OMIMref name="entrez" /> References External links * Further reading * * * * * * * * * * * * * * * {{gene-17-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLDN1
Claudin-1 is a protein that in humans is encoded by the ''CLDN1'' gene. It belongs to the group of claudins. Function Tight junctions represent one mode of cell-to-cell adhesion in epithelial or endothelial cell sheets, forming continuous seals around cells and serving as a physical barrier to prevent solutes and water from passing freely through the paracellular space. These junctions are composed of sets of continuous networking strands in the outwardly facing cytoplasmic leaflet, with complementary grooves in the inwardly facing extracytoplasmic leaflet. The protein encoded by this gene, a member of the claudin family, is an integral membrane protein and a component of tight junction strands. Loss of function mutations result in neonatal ichthyosis-sclerosing cholangitis syndrome. Interactions CLDN1 has been shown to interact with CLDN5 and CLDN3 Claudin 3, also known as CLDN3, is a protein which in humans is encoded by the ''CLDN3'' gene. It is a member of the claudin pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLDN3
Claudin 3, also known as CLDN3, is a protein which in humans is encoded by the ''CLDN3'' gene. It is a member of the claudin protein family. Tight junctions represent one mode of cell-to-cell adhesion in epithelial or endothelial cell sheets, forming continuous seals around cells and serving as a physical barrier to prevent solutes and water from passing freely through the paracellular space. These junctions are composed of sets of continuous networking strands in the outwardly facing cytoplasmic leaflet, with complementary grooves in the inwardly facing extracytoplasmic leaflet. The protein encoded by this intron-less gene, a member of the claudin family, is an integral membrane protein and a component of tight junction strands. It is also a low-affinity receptor for Clostridium perfringens enterotoxin, and shares amino acid sequence similarity with a putative apoptosis-related protein found in rat. Interactions CLDN3 has been shown to interact with CLDN1 and CLDN5 Claudin-5 i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLDN5
Claudin-5 is a protein that in humans is encoded by the ''CLDN5'' gene. It belongs to the group of claudins. Function This gene encodes a member of the claudin family. Claudins are integral membrane proteins and components of tight junction strands. Tight junction strands serve as a physical barrier to prevent solutes and water from passing freely through the paracellular space between epithelial or endothelial cell sheets. Mutations in this gene have been found in patients with velocardiofacial syndrome. Interactions CLDN5 has been shown to interact with CLDN1 and CLDN3 Claudin 3, also known as CLDN3, is a protein which in humans is encoded by the ''CLDN3'' gene. It is a member of the claudin protein family. Tight junctions represent one mode of cell-to-cell adhesion in epithelial or endothelial cell sheets, form .... References External links * Further reading * * * * * * * * * * * * * * {{gene-22-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tight Junction
Tight junctions, also known as occluding junctions or ''zonulae occludentes'' (singular, ''zonula occludens''), are multiprotein junctional complexes whose canonical function is to prevent leakage of solutes and water and seals between the epithelial cells. They also play a critical role maintaining the structure and permeability of endothelial cells. Tight junctions may also serve as leaky pathways by forming selective channels for small cations, anions, or water. The corresponding junctions that occur in invertebrates are septate junctions. Structure Tight junctions are composed of a branching network of sealing strands, each strand acting independently from the others. Therefore, the efficiency of the junction in preventing ion passage increases exponentially with the number of strands. Each strand is formed from a row of transmembrane proteins embedded in both plasma membranes, with extracellular domains joining one another directly. There are at least 40 different protei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tight Junction
Tight junctions, also known as occluding junctions or ''zonulae occludentes'' (singular, ''zonula occludens''), are multiprotein junctional complexes whose canonical function is to prevent leakage of solutes and water and seals between the epithelial cells. They also play a critical role maintaining the structure and permeability of endothelial cells. Tight junctions may also serve as leaky pathways by forming selective channels for small cations, anions, or water. The corresponding junctions that occur in invertebrates are septate junctions. Structure Tight junctions are composed of a branching network of sealing strands, each strand acting independently from the others. Therefore, the efficiency of the junction in preventing ion passage increases exponentially with the number of strands. Each strand is formed from a row of transmembrane proteins embedded in both plasma membranes, with extracellular domains joining one another directly. There are at least 40 different protei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occludin
Occludin is an enzyme ( EC 1.6) that oxidizes NADH. It was first identified in epithelial cells as a 65 kDa integral plasma-membrane protein localized at the tight junctions. Together with Claudins, and zonula occludens-1 (ZO-1), occludin has been considered a staple of tight junctions, and although it was shown to regulate the formation, maintenance, and function of tight junctions, its precise mechanism of action remained elusive and most of its actions were initially attributed to conformational changes following selective phosphorylation, and its redox-sensitive dimerization. However, mounting evidence demonstrated that occludin is not only present in epithelial/endothelial cells, but is also expressed in large quantities in cells that do not have tight junctions but have very active metabolism: pericytes, neurons and astrocytes, oligodendrocytes, dendritic cells, monocytes/macrophages lymphocytes, and myocardium. Recent work, using molecular modeling, supported by biochemical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmembrane Domain
A transmembrane domain (TMD) is a membrane-spanning protein domain. TMDs generally adopt an alpha helix topological conformation, although some TMDs such as those in porins can adopt a different conformation. Because the interior of the lipid bilayer is hydrophobic, the amino acid residues in TMDs are often hydrophobic, although proteins such as membrane pumps and ion channels can contain polar residues. TMDs vary greatly in length, sequence, and hydrophobicity, adopting organelle-specific properties. Functions of transmembrane domains Transmembrane domains are known to perform a variety of functions. These include: * Anchoring transmembrane proteins to the membrane. *Facilitating molecular transport of molecules such as ions and proteins across biological membranes; usually hydrophilic residues and binding sites in the TMDs help in this process. *Signal transduction across the membrane; many transmembrane proteins, such as G protein-coupled receptors, receive extracellular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conserved Sequence
In evolutionary biology, conserved sequences are identical or similar sequences in nucleic acids ( DNA and RNA) or proteins across species ( orthologous sequences), or within a genome ( paralogous sequences), or between donor and receptor taxa ( xenologous sequences). Conservation indicates that a sequence has been maintained by natural selection. A highly conserved sequence is one that has remained relatively unchanged far back up the phylogenetic tree, and hence far back in geological time. Examples of highly conserved sequences include the RNA components of ribosomes present in all domains of life, the homeobox sequences widespread amongst Eukaryotes, and the tmRNA in Bacteria. The study of sequence conservation overlaps with the fields of genomics, proteomics, evolutionary biology, phylogenetics, bioinformatics and mathematics. History The discovery of the role of DNA in heredity, and observations by Frederick Sanger of variation between animal insulins in 1949, prompt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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