Two forms of phosphatidylinositol-specific phospholipase C from bovine brain

Two immunologically distinct forms of phosphoinositide-specific phospholipase C were purified to near homogeneity from bovine brain. Their molecular weights determined by SDS-PAGE are 150,000 (enzyme I) and 145,000 (enzyme II), respectively. Under a nondenaturing condition, purified enzyme I exists mainly in dimeric form and as tetramer to a small extent, while enzyme II is predominantly in monomer, to a small extent as dimer and to a very small extent as trimer. Multiple forms of phosphoinositide-specific phospholipase C in brain tissue described in the literature might be, therefore attributed to the oligomerization of the two independent forms.