Altered activity of the nucleotide regulatory site in the parathyroid hormone-sensitive adenylate cyclase from the renal cortex of a patient with pseudohypoparathyroidism.

Published

Journal Article

A series of clinical studies suggest that the primary defect underlying pseudohypoparathyroidism is an abnormality of the parathyroid hormone-receptor-adenylate cyclase complex of the renal cortical cell plasma membrane. In the present study we compared parathyroid hormone-stimulated adenylate cyclase activity in membrane preparations from the renal cortex of three controls and a patient with pseudohypoparathyroidism. In the pseudohypoparathyroid preparation the Km for ATP was significantly greater and parathyroid hormone elicited markedly diminished adenylate cyclase activity at a subsaturating concentration of ATP. In contrast, the dose-response effect of enzyme activity to parathyroid hormone was the same in the control preparations, and that of the pseudohypoparathyroidism kidney, at a saturating concentration of ATP. The apparent alteration in enzyme kinetics, however, was normalized upon addition of guanosine 5'-triphosphate to the reaction mixtures. These results indicate that the defect in the parathyroid hormone-receptor-adenylate cyclase complex of the renal cell membranes, in our patient with pseudohypoparathyroidism, is an abnormal nucleotide receptor site of decreased activity. Such a defect may result in partial uncoupling of the parathyroid hormone receptor and adenylate cyclase, rendering the organ refractory to hormonal stimulation.

Full Text

Duke Authors

Cited Authors

  • Drezner, MK; Burch, WM

Published Date

  • December 1, 1978

Published In

Volume / Issue

  • 62 / 6

Start / End Page

  • 1222 - 1227

PubMed ID

  • 219026

Pubmed Central ID

  • 219026

International Standard Serial Number (ISSN)

  • 0021-9738

Digital Object Identifier (DOI)

  • 10.1172/JCI109242

Language

  • eng

Conference Location

  • United States