Abstract
The nature of the outer surface of isolated lysosomes from rat livers was investigated by electron microscopic cytochemistry. After incubations with ferritin conjugated reagents, the outer surface of isolated lysosomal membrane revealed an intense binding for cationized ferritin (CF) and a moderate binding for ferritin conjugated wheat germ agglutinin (WGA-F), but not for anionized ferritin and ferritin conjugated Concanavalin A. Although CF particles were uniformly distributed on all lysosomal membranes, WGA-F particles showed a non-uniform distribution pattern, varying from lysosome to lysosome. These results suggest that the outer surface of the lysosomal membrane contains a net negative charge which is partially caused by N-acetylneuraminic acid judging from its characteristic of binding to WGA. The negative charges on the lysosomal membrane toward the cytoplasmic side may regulate the interaction of other organelle membrane with the lysosomal membrane.
