Functional modification of the guanine nucleotide regulatory protein after desensitization of turkey erythrocytes by catecholamines.

Journal Article (Journal Article)

Densensitization of turkey erythrocytes by exposure to the beta-adrenergic agonist (-)isoproterenol leads to decreased activation of adenylate cyclase by agonist, NaF, and guanyl-5'-yl imido diphosphate, with no reduction in the number of beta-adrenergic receptors. Interactions between the receptor and the guanine nucleotide regulatory protein (N protein) also seem to be impaired. These observations suggest that a component distal to the beta-adrenergic receptor may be a locus of modification. Accordingly we examined the N protein to determine whether it was altered by desensitization. The rate at which (-)isoproterenol stimulated the release of [3H]GDP from the N protein was substantially lower in membranes prepared from desensitized cells, providing further evidence for uncoupling of the receptor and the N protein. The amount of N protein in membranes from control and desensitized cells was compared by labeling the 42,000 Mr component of the N protein with [32P]NAD+ and cholera toxin; no significant difference was found. However, significantly more N protein (p less than .001) was solubilized by cholate extraction of desensitized membranes, suggesting an altered association of the N protein with the membrane after desensitization. The functional activity of the N protein was measured by reconstitution of cholate extracts of turkey erythrocyte membranes into S49 lymphoma cyc- membranes. Reconstitution of (-)isoproterenol stimulation of adenylate cyclase activity was reduced significantly (p less than .05) after desensitization. These observations suggest that desensitization of the turkey erythrocyte by (-)isoproterenol results in functional modifications of the guanine nucleotide regulatory protein, leading to impaired interactions with the beta-adrenergic receptor and reduced activation of adenylate cyclase.

Full Text

Duke Authors

Cited Authors

  • Briggs, MM; Stadel, JM; Iyengar, R; Lefkowitz, RJ

Published Date

  • July 1, 1983

Published In

Volume / Issue

  • 224 / 1

Start / End Page

  • 142 - 151

PubMed ID

  • 6307146

International Standard Serial Number (ISSN)

  • 0003-9861

Digital Object Identifier (DOI)

  • 10.1016/0003-9861(83)90198-4


  • eng

Conference Location

  • United States