Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The delivery of water channels to the apical membrane in response to antidiuretic hormone (ADH) requires the targeting of channel-containing vesicles to specific sites in the membrane, followed by fusion and exocytosis. A complex array of proteins is now believed to mediate targeting and fusion in eukaryotic cells. They include N-ethylmaleimide-sensitive fusion protein (NSF), soluble NSF attachment proteins (SNAP), and cellubrevin, a vesicle-associated protein present in the nerve terminal. We asked whether these proteins are in epithelial cells of rat inner medullary collecting duct (IMCD) and amphibian bladder. Immunoblots on both tissues showed the presence of NSF and alpha-SNAP. Cellubrevin was present in immunoblots of the IMCD, but not the bladder. Immunogold electron microscopy showed NSF, alpha-SNAP, and cellubrevin in rat IMCD cells, with vesicular labeling. In the bladder, NSF was seen on vesicles and aggrephores. We conclude that components of the vesicle-targeting and fusion systems are present in kidney and amphibian bladder and may mediate a wide variety of fusion events, including those initiated by ADH.
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PMID:Vesicle fusion proteins in rat inner medullary collecting duct and amphibian bladder. 790 Jul 82

H(+) transport in the collecting duct is regulated by exocytic insertion of H(+)-ATPase-laden vesicles into the apical membrane. The soluble N-ethylmaleimide-sensitive fusion protein attachment protein (SNAP) receptor (SNARE) proteins are critical for exocytosis. Syntaxin 1A contains three main domains, SNARE N, H3, and carboxy-terminal transmembrane domain. Several syntaxin isoforms form SNARE fusion complexes through the H3 domain; only syntaxin 1A, through its H3 domain, also binds H(+)-ATPase. This raised the possibility that there are separate binding sites within the H3 domain of syntaxin 1A for H(+)-ATPase and for SNARE proteins. A series of truncations in the H3 domain of syntaxin 1A were made and expressed as glutathione S-transferase (GST) fusion proteins. We determined the amount of H(+)-ATPase and SNARE proteins in rat kidney homogenate that complexed with GST-syntaxin molecules. Full-length syntaxin isoforms and syntaxin-1ADeltaC [amino acids (aa) 1-264] formed complexes with H(+)-ATPase and SNAP23 and vesicle-associated membrane polypeptide (VAMP). A cassette within the H3 portion was found that bound H(+)-ATPase (aa 235-264) and another that bound SNAP23 and VAMP (aa 190-234) to an equivalent degree as full-length syntaxin. However, the aa 235-264 cassette alone without the SNARE N (aa 1-160) does not bind but requires ligation to the SNARE N to bind H(+)-ATPase. When this chimerical construct was transected into inner medullary collecting duct cells it inhibited intracellular pH recovery, an index of H(+)-ATPase mediated secretion. We conclude that within the H3 domain of syntaxin 1A is a unique cassette that participates in the binding of the H(+)-ATPase to the apical membrane and confers specificity of syntaxin 1A in the process of H(+)-ATPase exocytosis.
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PMID:Syntaxin 1A has a specific binding site in the H3 domain that is critical for targeting of H+-ATPase to apical membrane of renal epithelial cells. 1587 13