INTERACTION OF RAT-LIVER LYSOSOMES WITH BASIC POLYPEPTIDES

In order to gain knowledge on the interaction of lysosomes with proteins, we have assessed the equilibrium densities of the lysosomal membrane and matrix markers after in vitro incubation of rat liver lysosomes with various polypeptides. The addition of basic polypeptides, polylysine or protamine, to the suspension of lysosomes brought about a profound alteration of lysosomal membrane, causing extensive leakage of lysosomal matrix enzymes. Electron microscopic observation revealed a remarkable aggregation of lysosomes by the basic polypeptides. Polyglutamic acid, an acidic polypeptide, did not produce such effect. ATP was found to stabilize lysosomes during incubation, particularly with basic polypeptides.