GTP gamma S binding activities were reduced in heavy membrane fraction during desensitization by Ca-mobilizing agonists in human astrocytoma cells
Nakahata, N.; Matsuoka, I.; Suzuki, T.; Nakanishi, H.
Research Communications in Chemical Pathology and Pharmacology 64(2): 179-192
1989
ISSN/ISBN: 0034-5164 PMID: 2500683 Document Number: 346124
Carbachol, histamine and bradykinin activate phospholipase C in pertussis toxin-insensitive manner in human astrocytoma cells. Pretreatments of the cells with these agonists resulted in the reduction of GTP gamma S-induced accumulation of inositol phosphates in membrane preparations. Treatment of cells with carbachol mobilized GTP gamma S binding activities as well as muscarinic receptors from heavy membrane fraction to light fraction, reflecting from an agonist-induced desensitization. The treatment of the cells with agonists reduced a 32 kDa GTP binding protein in heavy membrane fraction, determined by a photoaffinity labeling with [35S]GTP gamma S. The data suggest that the 32 kDa GTP binding protein is involved in desensitization by agonists which activate phospholipase C in human astrocytoma cells.