GTP gamma S binding activities were reduced in heavy membrane fraction during desensitization by Ca-mobilizing agonists in human astrocytoma cells.
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.
Nakahata
N
N
Department of Pharmacology, Fukushima Medical College, Japan.
Matsuoka
I
I
Suzuki
T
T
Nakanishi
H
H
D000345:Affinity Labels; D001254:Astrocytoma / Q000378:metabolism* / Q000648:ultrastructure; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D019204:GTP-Binding Proteins / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D006801:Humans; D008566:Membranes / Q000378:metabolism; D009374:Neoplasms, Experimental / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding; D011976:Receptors, Muscarinic / Q000187:drug effects; D013873:Thionucleotides / Q000378:metabolism*
D000345:Affinity Labels; D002120:Calcium Channel Agonists; D011976:Receptors, Muscarinic; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins