Upon detergent or hypo-osmotic lysis of CHO-cell postnuclear supernatants or isolated lysosomes at pH 4.8, the lysosomal enzymes beta-hexosaminidase, beta-galactosidase, alpha-fucosidase and cathepsin C were readily pelleted, whereas the exogenous marker, long-term-internalized horseradish peroxidase, was not. Salt or pH elevation greatly decreased lysosomal-enzyme pelletability. The results suggest that, under native conditions, lysosomal hydrolases may be aggregated. Aggregation could promote enzyme retention within the organelle.
