The role of glycosidically bound mannose in the assimilation of β-galactosidase by generalized gangliosidosis fibroblasts

Bovine testicular β-galactosidase is rapidly assimilated by generalized gangliosidosis skin fibroblasts. The enzyme contains equimolar amounts of mannose and glucosamine and strongly binds to concanavalin A-Sepharose. Pretreatment of β-galactosidase with a mannosidase preparation from $\text{Aspergillus}\text{niger}$ reduced the rate of assimilation of the enzyme 97%. These data indicate that mannosyl residues play a role in assimilation of the enzyme. This conclusion is supported by observed inhibition of β-galactosidase assimilation by mannose, methyl α- and β-mannopyranosides, and mannose-containing testicular glycoproteins.