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AKITA, YOSHIKO, TOSHIKAZU SAITO, YUKIKO YAJIMA, SHIN SAKUMA, The Stimulatory and Inhibitory Guanine Nucleotide-Binding Proteins of Adenylate Cyclase in Erythrocytes from Patients with Pseudohypoparathyroidism Type I, The Journal of Clinical Endocrinology & Metabolism, Volume 61, Issue 6, 1 December 1985, Pages 1012–1017, https://doi.org/10.1210/jcem-61-6-1012
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Abstract
Both the inhibitory and stimulatory guanine nucleotide-binding proteins of the adenylate cyclase complex were measured in erythrocyte membranes from patients with pseudohypoparathyroidism (PHP). The inhibitory guanine nucleotide- binding protein (Ni) of adenylate cyclase was measured by incorporation of [32P]ADP-ribose from [32P]NAD into the 39K subunit of Ni catalyzed by pertussis toxin. The ADPribosyltransferase activity of the toxin was expressed through incubation with dithiothreitol and erythrocyte membranes. Erythrocytes from 12 patients with PHP type I (PHP-I) had Ni values similar to those of 9 normal subjects and 2 patients with pseudopseudohypoparathyroidism. In 6 PHP-I patients, decreased activity of the stimulatory guanine nucleotide-binding protein (Ns) of adenylate cyclase, as determined by reconstitution of adenylate cyclase in the Ns-deficient membranes of eye” S49 cells, corresponded with the reduced degree of ADP-ribosylation of the 42K subunit of Ns catalyzed by cholera toxin. These data suggest that the defect of Ns results in reduced stimulation of adenylate cyclase in some PHP-I patients, and that enhanced inhibition of the enzyme due to an increase in the 39K subunit of Ni does not account for the biochemical lesion in PHP-I patients.
