Abstract
We have previously demonstrated that 5'-nucleotidase, known as a plasma membrane enzyme, is also distributed both in rat liver tritosomal membranes and contents (J. Biochem. 101, 1077-1085, 1987). When the lysosomal membranes isolated from rat livers were incubated with phosphatidylinositol-specific phospholipase C purified from B. thuringiensis, about 70% of 5'-nucleotidase activity was released from the membranes. Judging from the result by phase separation with Triton X-114, the enzyme solubilized by the phospholipase C digestion showed a hydrophilic nature such as that of the tritosomal contents. Immunoblot analysis showed that the molecular weight of 5'-nucleotidase released from the lysosomal membranes by the phospholipase C digestion was almost identical with that of the enzymes from the Tritosomal contents. The above results showed that the phosphatidylinositol-specific phospholipase C-like enzyme in the lysosomes may be responsible for the conversion of the lysosomal membrane-bound 5"-nucleotidase to the soluble form present in the lysosomal matrix.
