The carbohydrate moiety of the activator protein for glucosylceramide beta-glucosidase.
SAP-2 is a family of heat-stable, acidic glycoproteins which stimulate enzymatic hydrolysis of glucosylceramide. We studied the carbohydrate moieties of a ConA-binding form of SAP-2. The protein contained glucosamine, galactose, mannose, and fucose; galactosamine and sialic acid were not detectable. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining showed three bands of 6.5, 8.5, and 10 kDa. After deglycosylation with peptide N-glycosidase, SAP-2 eluted more slowly from the C4 column and showed a single band of 4 kDa. From carbohydrate analysis it was evident that deglycosylation had removed more than 90% of the sugars. These data indicate that SAP-2 possesses N-linked complex or hybrid type oligosaccharide chains. The specific activity of the deglycosylated protein in the glucosidase stimulation assay was unaffected.
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Mental Health Research Institute, University of Michigan, Ann Arbor 48109.
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D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D003208:Concanavalin A / Q000378:metabolism; D004789:Enzyme Activation; D005959:Glucosidases / Q000378:metabolism*; D005962:Glucosylceramidase / Q000378:metabolism*; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism; D006168:Guinea Pigs; D008099:Liver / Q000201:enzymology*; D008970:Molecular Weight; D049231:Saposins; D049128:Sphingolipid Activator Proteins
D000596:Amino Acids; D002241:Carbohydrates; D006023:Glycoproteins; D049231:Saposins; D049128:Sphingolipid Activator Proteins; D003208:Concanavalin A; D005959:Glucosidases; D005962:Glucosylceramidase