The hydrolysis of phosphatidylinositol 4-phosphate in membranes of Xenopus laevis oocytes: characteristics of a phosphomonoesterase.
1. Phosphatidylinositol 4-phosphate (PtdIns4P) is degraded by isolated membranes from Xenopus laevis oocytes. 2. Incubation of [4-32P]PtdIns4P with membranes yields only radioactive inorganic phosphate, indicating the presence of a phosphomonoesterase. 3. Membranes hydrolyze Ptd[2-3H]Ins4P to produce mainly Ptd[2-3H]Ins in the lipid phase. In this incubation [3H]inositol and inositol monophosphate appear in the water phase. 4. Membrane incubations of Ptd[2-3H]Ins4P carried out in the presence of excess non-radioactive Ins(1,4)P2 allows the trapping of small amounts of [3H]Ins(1,4)P2. These results demonstrate the presence of a phospholipase C. 5. Testing several phosphorylated analogs, it is determined that fructose 1,6-bisphosphate and alpha-glycerophosphate are potent inhibitors of the oocyte PtdIns4P phosphomonoesterase.
Jacob
G
G
Departamento de Bioquímica, Facultad de Medicina, Universidad de Chile, Santiago.
Allende
C C
CC
Allende
J E
JE
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005635:Fructosediphosphates / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D009865:Oocytes / Q000378:metabolism* / Q000648:ultrastructure; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism; D014982:Xenopus laevis
D005635:Fructosediphosphates; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; C037178:phosphatidylinositol 4-phosphate; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase; D010738:Type C Phospholipases; C029063:fructose-1,6-diphosphate