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Characterization of a G protein-coupled guanylyl cyclase-B receptor from bovine tracheal smooth muscle

Abstract:

A G protein-coupled natriuretic peptide-guanylyl cyclase receptor-B (NPR-B) located in plasma membranes from bovine tracheal smooth muscle shows complex kinetics and regulation. NPR-B was activated by natriuretic peptides (CNP-53 > ANP-28) at the ligand extracellular domain, stimulated by Gq-protein activators, such as mastoparan, and inhibited by Gi-sensitive chloride, interacting at the juxtamembrane domain. The kinase homology domain was evaluated by the ATP inhibition of Mn 2+ -activated NPR-B, which was partially reversed by mastoparan. The catalytic domain was studied by kinetics of Mn 2+/Mg 2+ and GTP, and the catalytic effect with GTP analogues with modifications of the β/γ phosphates and ribose moieties. Most NPR-B biochemical properties remained after detergent solubilization but the mastoparan activation and chloride inhibition of NPR-B disappeared. Our results indicate that NPR-B is a highly regulated nano-machinery with domains acting at cross-talk points with other signal transducing cascades initiated by G protein-coupled receptors and affected by intracellular ligands such as chloride, Mn 2+ , Mg 2+ , ATP, and GTP. Copyright © Informa Healthcare.