Characteristics and regulation of high affinity ( sup 125 )calcitonin gene-related peptide (*CGRP) binding sites in cultured neonatal rat cardiac myocytes

Conference · Mon Mar 11 04:00:00 EST 1991 · FASEB Journal (Federation of American Societies for Experimental Biology); (United States)

OSTI ID:5865491

Fisher, R A; Moy, J A; Chatterjee, T K ^[1]

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1. Univ. of Iowa, Iowa City (United States)

In the present study, the characteristics and regulation of *CGRP binding sites in cultured cardiac myocytes were investigated. Binding of *CGRP to membranes prepared from these cells was selective, saturable and of high affinity. Scatchard transformation of the saturation isotherm generated a linear plot suggesting the existence of a homogeneous population of binding sites with a KD of 41 {plus minus} 7 pM and Bmax of 31 {plus minus} 5 fmol/mg protein. Binding of CGRP to membranes was inhibited completely by guanosine 5'-(3-O-thio)triphosphate (GTPS) (250 {mu}M) suggesting association of the binding sites with a G protein. Consistent with the saturation binding data, association kinetic studies indicated that *CGRP associated with a single population of binding sites. Dissociation kinetic data, in contrast, indicated that *CGRP dissociated from two affinity component sites on membranes suggesting the existence of multiple affinity states of the G protein-coupled forms of the receptor. Non-equilibrium dissociation kinetic experiments revealed a time-dependent alteration in the fraction of the *CGRP binding sites dissociating with a fast and slow rate. Prior exposure of cells to CGRP (10 nM) for 5 min caused nearly 80% attenuation of the maximal cellular cAMP response to further CGRP challenge and a 75% reduction of the number of *CGRP binding sites in membranes prepared from these cells.

• OSTI ID: 5865491
• Report Number(s): CONF-9104107--
• Conference Information: Journal Name: FASEB Journal (Federation of American Societies for Experimental Biology); (United States) Journal Volume: 5:4
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BODY
CARDIOVASCULAR SYSTEM
CELL CULTURES
CHEMICAL COMPOSITION
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HEART
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
NEONATES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDES
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
TRACER TECHNIQUES
VERTEBRATES