The Ins(1,4,5)P3 binding site of bovine adrenocortical microsomes: function and regulation.
Adrenocortical microsomes possess a single population of Ins(1,4,5)P3-specific binding sites [IC50 5.9 +/- 0.9 nM; Palmer, Hughes, Lee & Wakelam (1988) Cell. Signalling 1, 147-156]. Competition studies showed that Ins(1:2-cyclic,4,5)P3 exhibits a 21-fold lower affinity for the site than Ins(1,4,5)P3 (IC50 124 +/- 16 nM). The affinity of the binding sites for Ins(1,4,5)P3 was not influenced by the non-hydrolysable GTP analogues GTP gamma S and Gpp[NH]p or by preincubation of the binding protein with a preparation of partially purified protein kinase C in the presence of ATP and TPA (12-O-tetradecanoylphorbol 13-acetate). These observations are discussed with reference to the identify and function of the Ins(1,4,5)P3 binding site.
Palmer
S
S
Molecular Pharmacology Group, Institute of Biochemistry, University of Glasgow, U.K.
Wakelam
M J
MJ
D000302:Adrenal Cortex / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001667:Binding, Competitive; D015220:Calcium Channels; D002417:Cattle; D019204:GTP-Binding Proteins / Q000502:physiology; D015544:Inositol 1,4,5-Trisphosphate; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism*; D011493:Protein Kinase C / Q000502:physiology; D011956:Receptors, Cell Surface / Q000502:physiology*; D018160:Receptors, Cytoplasmic and Nuclear; D013403:Sugar Phosphates / Q000378:metabolism*
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D013403:Sugar Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D011493:Protein Kinase C; D019204:GTP-Binding Proteins