Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Classical techniques for studying modulations of microvascular permeability have a time resolution of minutes. A newly developed method allows continuous measurement of the electrical resistance of the microvascular membrane in vivo (Olesen & Crone 1983). The technique exploits microelectrodes impaled into the vascular lumen and is based on cable analysis of the vessel. It was applied to venules on the surface of the frog brain to test the effect on microvascular permeability of a wide variety of substances. The following agents increased ionic permeability reversibly within seconds: 5-hydroxytryptamine, bradykinin, ATP, ADP, AMP, phospholipase A2, arachidonic acid, leukotriene C4, oxygen-derived free radicals, ionophore A23187, and unbound Evans blue dye. An irreversible permeability increase was induced by protamine sulphate, neuraminidase, trypsin, melittin, and snake venoms from Crotalus durissus terrificus and Bothrops atrox. The following substances were without effect within an administration period of 5 min: histamine, epinephrine, putrescine, angiotensin II, vasoactive intestinal polypeptide (VIP), substance P, neurotensin, vasopressin, adenosine, PGE2, PGF2 alpha, prostacyclin (PGI2), leukotriene B4, albumin, heparin, plant cytokinins, hyaluronidase, thrombin, wasp venom. Variations in pH between 5.1 and 8.6 did not change permeability. Three conclusions are drawn from the observations: (1) the permeability of cerebral microvessels can be modulated by specific agents, (2) the agents induced changes in the endothelium within a few seconds, and (3) the rapid permeability increase induced by inflammatory mediators was less than two-fold and reversible within minutes.
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PMID:Substances that rapidly augment ionic conductance of endothelium in cerebral venules. 348 16

Cultured A6 epithelial cells from toad kidney form confluent monolayers with tight junctions separating the apical and basolateral membranes. These two membrane domains have distinct compositions and functions. Thus, sodium is actively transported across the epithelia from the apical to basolateral surface via amiloride-inhibitable sodium channels located in the apical membrane. Sodium transport is stimulated by vasopressin, cholera toxin, and 8-bromo-cAMP applied to the basolateral surface where the receptors, adenylate cyclase, and Na+/K+-ATPase are located. In a previous study (Spiegel, S., Blumenthal, R., Fishman, P.H., and Handler, J.S. (1985) Biochim. Biophys. Acta 821, 310-318), we demonstrated that exogenous gangliosides inserted into the apical membrane of A6 epithelia do not redistribute to the basolateral membrane. With the ability to vary selectively the ganglioside composition of the apical membrane, we examined the effects of gangliosides on sodium transport in A6 epithelia. When the apical surface of A6 epithelia were exposed to exogenous gangliosides, sodium transport in response to vasopressin, cholera toxin, and 8-bromo-cAMP was enhanced compared to epithelia not exposed to gangliosides. The effect was observed with bovine brain gangliosides, NeuAc alpha 2----3Gal beta 1----3GalNAc beta 1----4[NeuAc alpha 2----3]Gal beta 1----4Glc beta 1----Cer (GD1a) and Gal beta-1----3GalNAc beta 1----4[NeuAc alpha 2----3]Gal beta 1----4Glc beta 1----Cer (GM1), but not with the less complex ganglioside, Neu-Ac alpha 2----3Gal beta 1----4Glc beta 1----Cer (GM3). We examined A6 cells for endogenous gangliosides and found that, whereas GM3 was a major ganglioside, only trace amounts of GM1 and GD1a were present. Based on cell surface and metabolic labeling studies, these gangliosides were synthesized by the cells and were present on the apical as well as the basolateral surface. Bacterial sialidase, which hydrolyzes more complex gangliosides to GM1, was used to modify the endogenous gangliosides on the apical surface; after sialidase treatment, the epithelia were more responsive to vasopressin, cholera toxin, and 8-bromo-cAMP. Thus, gangliosides may be modulators of sodium channels present in the apical membrane of epithelial cells.
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PMID:Gangliosides modulate sodium transport in cultured toad kidney epithelia. 378 88

The human V2 vasopressin receptor contains one consensus site for N-linked glycosylation at asparagine 22 in the predicted extracellular amino terminal segment of the protein. This segment also contains clusters of serines and threonines that are potential sites for O-glycosylation. Mutagenesis of asparagine 22 to glutamine abolished N-linked glycosylation of the V2 receptor (N22Q-V2R), without altering its function or level of expression. The N22Q-V2R expressed in transfected cells migrated in denaturing acrylamide gels as two protein bands with a difference of 7000 Da. Protein labeling experiments demonstrated that the faster band could be chase to the slower one suggesting the presence of O-linked sugars. Sialidase treatment of membranes from cells expressing the N22Q-V2R or of immunoprecipitated metabolically labeled V2R accelerated the migration of the protein in acrylamide gels demonstrating the existence of O-glycosylation, the first time this type of glycosylation has been found in a G protein coupled receptor. Synthesis of metabolically labeled receptor in the presence of 1 mM phenyl-N-acetyl-alpha-D-galactosaminide, a competitive inhibitor of N-acetyl-alpha-D-galactose and N-acetylneuraminic acid transferases, also produced a receptor that migrated faster in denaturing gels. Serines and threonines present in the amino terminus were analyzed by alanine scanning mutagenesis to identify the acceptor sites. O-glycosylation was found at most serines and threonines present in the amino terminus. Because the disappearance of a site opened the availability of others to the transferases, the exact identification of the acceptor sites was not feasible. The wild type V2R expressed in HEK 293, COS, or MDCK cells underwent N- and O-linked glycosylation. The mutant V2R bearing all serine/threonine substitutions by alanine at the amino terminus yielded a receptor functionally indistinguishable from the wild type protein, whose mobility in polyacrylamide gels was no longer affected by sialidase treatment.
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PMID:O-Glycosylation of the V2 vasopressin receptor. 1036 43