Differential uptake of D-galactosyl- and D-glucosyl-neoglycoproteins by isolated rat hepatocytes.
Bovine serum albumin was modified with 2-imino-2-methoxyethyl 1-thioglycopyranosides of galactose and glucose (Gal-AI-BSA, Glc-AI-BSA, respectively). Both types of neoglycoproteins were taken up by isolated rat hepatocytes. Gal-AI-BSA and Glc-AI-BSA inhibited the uptake of each other, and also inhibited the uptake of asialo-orosomucoid as expected from the results obtained with rabbit liver membranes (Stowell, C. P., and Lee, Y. C. (1978) J. Biol. Chem. 253, 6107-6110). Gal-neoglycoproteins of bovine serum albumin containing other linking groups between the galactose moiety and protein were found to be as effective in inhibition of the uptake of asialo-orosomucoid as Gal-AI-BSA, indicating that the method of carbohydrate attachment had little influence on endocytosis of galactose-terminated neoglycoproteins. In contrast, comparable Glc-neoglycoproteins (other than Glc-AI-BSA) were weak inhibitors. It thus appears that the positively charged amidino group present in Glc-AI-BSA contributes to the uptake of this neoglycoprotein by rat hepatocytes.
D000818:Animals; D001667:Binding, Competitive; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D006023:Glycoproteins / Q000138:chemical synthesis / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins; D009961:Orosomucoid / Q000378:metabolism; D033902:Periplasmic Binding Proteins; D011817:Rabbits; D051381:Rats; D012709:Serum Albumin; D013329:Structure-Activity Relationship
D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D006023:Glycoproteins; D009004:Monosaccharide Transport Proteins; D009961:Orosomucoid; D033902:Periplasmic Binding Proteins; D012709:Serum Albumin; C023550:galactose-binding protein; D005690:Galactose