Guanine nucleotides stimulate hydrolysis of phosphatidylinositol and polyphosphoinositides in permeabilized Swiss 3T3 cells.
Hydrolysis-resistant analogues of GTP specifically stimulate the formation of [3H]inositol mono-, bis- and trisphosphates by saponin-permeabilized Swiss 3T3 cells prelabelled with [3H]inositol. Each inositol phosphate is formed largely by hydrolysis of its parent lipid and not by dephosphorylation of inositol 1,4,5-trisphosphate [(1,4,5)IP3]. Although hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) is most sensitive to guanine nucleotides, hydrolysis of phosphatidyl-inositol (PI) and phosphatidylinositol 4-phosphate (PIP) is quantitatively more important. These results suggest that a guanine nucleotide-dependent regulatory protein(s) (G-protein) is involved in regulating the hydrolysis of PI and PIP, as well as PIP2, and so may allow formation of diacylglycerol (DG) without simultaneous production of (1,4,5)IP3 and mobilization of intracellular Ca2+.
Taylor
C W
CW
AFRC Unit of Insect Neurophysiology and Pharmacology, Department of Zoology, Cambridge, England.
Blakeley
D M
DM
Brown
K D
KD
D000818:Animals; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D006150:Guanine Nucleotides / Q000494:pharmacology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007295:Inositol Phosphates / Q000096:biosynthesis*; D007700:Kinetics; D051379:Mice; D009355:Neomycin / Q000494:pharmacology; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000378:metabolism*; D012016:Reference Values; D013403:Sugar Phosphates / Q000096:biosynthesis*; D013873:Thionucleotides / Q000494:pharmacology
D006150:Guanine Nucleotides; D007295:Inositol Phosphates; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D013403:Sugar Phosphates; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D009355:Neomycin