Vasopressins protein binding

This transmembrane signaling system involves a complex consisting of several functional proteins (Figure 7) stimulatory (e.g. P-adrenergic, dopamine Dp serotonin, vasopressin) [124] and inhibitory (e.g. a2-adrenergic, dopamine D2, opiod, and muscarinic) [125] receptors, stimulatory (Gs) and inhibitory (G ) G-proteins, and the catalytic protein, adenylate cyclase. On stimulation of a receptor, an associated G-protein binds GTP and the resulting receptor/G-protein/GTP complex then activates, or inhibits, adenylate cyclase in the catalysis of the synthesis... 

The Argl37His AVPR2 variant has been the subject of detailed study in heterologous expression systems (123). Vasopressin binds the variant with affinity similar to the wild type however, it fails to stimulate G a. This evidence suggests that the conservation of an arginine at this position is necessary for receptor-coupled G protein activity (115,123,124). 

P) of surface membranes to Ca2+, Na+, and K+. The resulting depolarization or hyperpolarization of the sensory cell (the signal) is passed through relay neurons to sensory centers in the brain. In the best-studied cases, desensitization includes phosphorylation of the receptor and binding of a protein (arrestin) that interrupts receptor-G protein interactions. VR is the vasopressin receptor other receptor and G protein abbreviations are as used in earlier illustrations. 

The cq receptors are activated not only by catecholamines but also by the hormones vasopressin and angiotensin n. Binding of these hormones to a, receptors induces a complex response that involves rapid hydrolysis of phosphatidylinositol derivatives and release of Ca2+ into die cytoplasm, and of diacylglycerols into the lipid bilayer of the membrane. The response is mediated by another G protein called Gq.27 1 275 When this G protein is activated it induces the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdInsP2), a normal minor component of the lipid bilayer, by phospholipase C (phosphoinositidase C).265,276 281... 

Every hormone must have one or more receptors, most of which are proteins. These may be found embedded in the outer surface of the plasma membrane, in the cytoplasm, or in the cell nucleus. Binding of a hormone to its receptor often elicits both a rapid response and a slower one. For example, we have seen that glucagon, adrenaline, and vasopressin bind to cell surface receptors and promote the synthesis of cyclic AMP (Fig. 11-4). Tire cAMP induces rapid chemical modifications of many proteins. Some of these may diffuse into the nucleus and affect transcription of genes, a slower response. Insulin (Chapter 11, Section G) also exerts both rapid and slower responses. 

It increases the water permeability of the kidney collecting duct cells by inducing translocation of aqua-porin proteins from intracellular storage vesicles into the apical plasma membrane.78 Vasopressin binds to... 

Key Words Bradykinin chimerism galparan G protein-coupled receptor ligand binding mastoparan secretion vasopressin. 

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