M1 muscarinic choligernic receptor, Gq and G11 (G q 11), and phospholipase C-β1 were highly purified from both natural sources and cells that express the appropriate cDNA's. When the proteins were co-reconstituted in into phospholipid vesicles, the receptor efficiently and selectively promoted the activation of if G q 11, leading to marked stimulation of PLC activity in the presence of GTPγS. No stimulation was observed in the presence of GTP, however, which led to the finding that PLC-β1 stimulates the hydrolysis of if G q 11-bound GTP at leasr 50-fold. Thus, PLC-β1 is a GTPase activating protein, a GAP, for its physiologic regulator G in q 11. We discuss the implications of PLC- β1's GAP activity on the M1 muscarinic cholinergic signaling pathway.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)