Resolution and characterization of two forms of phosphoinositide-specific phospholipase C from bovine rod outer segments.
Two forms (I and II) of phospholipase C, specific for phosphatidyl inositol 4,5-bisphosphate, were resolved from bovine retinal rod outer segment (ROS) cytosol by DEAE-Sepharose column chromatography. The two isozymes showed reproducible differences in their catalytic properties in spite of similar substrate specificity and hydrolyzed specifically inositol 4,5-bisphosphate in a Ca(2+)-dependent fashion. In the presence of deoxycholate (DOC), pH optima were at 6.5 and 7.0 for phospholipase C I and II, respectively. Maximal phosphatidylinositol 4,5-bisphosphate hydrolysis rates were obtained at 10(-4) and 10(-5)M Ca2+ for phospholipase C I and II, respectively. Treatment with cAMP-dependent protein kinase did not alter either isozyme activity. Further purification steps were prevented by the extreme lability of the isozymes.
Panfoli
I
I
Istituto Policattedra di Chimica Biologica, Università di Genova.
Morelli
A
A
Pepe
I M
IM
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010727:Phosphoric Diester Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D012374:Rod Cell Outer Segment / Q000201:enzymology*; D012995:Solubility
D007527:Isoenzymes; D010727:Phosphoric Diester Hydrolases; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D002118:Calcium