Characteristic [3H]glucosamine-labeled glycoproteins in two-dimensional electrophoretograms of human renal cancer cells: identification as cathepsin D.
Two-dimensional electrophoretograms of extracts of [3H]glucosamine-labeled human renal cancer cells demonstrated a series of components (Mr 48,000 and 30,000) that are only poorly expressed in similarly labeled normal kidney epithelial cell cultures [S. Ogata, R. Ueda, and K. O. Lloyd (1981) Proc. Natl. Acad Sci. USA 78, 770-774]. These characteristics are also exhibited by [3H]Man-labeled samples and by concanavalin A-binding glycoproteins from [35S]Met-labeled cells. It is now shown that these species are the precursor chain (Mr 48,000) and native heavy chain (Mr 30,000) forms of the lysosomal enzyme, cathepsin D. These results were obtained by precipitation with a specific anti-cathepsin D serum and by binding of the components to pepstatin-Sepharose. Cathepsin D heavy chain is heterogeneous, having three major species with pI's of 5.7, 5.3, and 4.9; all forms are glycosylated with high mannose-type chains [approximate size: Man5(GlcNAc)2] and are partially phosphorylated. Despite these indications of dissimilarities in cathepsin D levels, the actual levels of total acid protease activity were not significantly higher in renal cancer cells than in normal kidney epithelial cells.
D016282:Aspartic Acid Endopeptidases; D002241:Carbohydrates / Q000032:analysis; D002402:Cathepsin D / Q000302:isolation & purification*; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000032:analysis; D004792:Enzyme Precursors / Q000302:isolation & purification; D006023:Glycoproteins / Q000302:isolation & purification; D006801:Humans; D007668:Kidney / Q000032:analysis; D007680:Kidney Neoplasms / Q000032:analysis*; D008970:Molecular Weight
D002241:Carbohydrates; D004792:Enzyme Precursors; D006023:Glycoproteins; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; D002402:Cathepsin D