Structure-function relationships in glucosidase I: amino acids involved in binding the substrate to the enzyme.
As the enzyme that initiates the maturation phase of the oligosaccharide moiety of N-linked glycoproteins, glucosidase I controls the flux of carbohydrate during the biosynthesis of these proteins. In a previous study to elucidate the structure-function relationships, we reported the presence of a cysteine residue at or near the active site of the enzyme from the bovine mammary gland (Pukazhenthi,B.S., Muniappa,N. and Vijay,I.K., 1993, J. Biol. Chem., 268, 6445-6452). We have now extended this approach to identify the participation of an arginine and a tryptophan residue in the enzyme that may play an important role in binding the substrate. The data have been combined with the results of the previous study and the cDNA-derived sequence to propose a ERHLDLRCW motif in the active site of the enzyme in the rat mammary gland that is involved in binding the incipient glycoprotein substrate for processing.
Romaniouk
A
A
Department of Animal Sciences, University of Maryland, College Park 20742, USA.
Vijay
I K
IK
D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine; D001665:Binding Sites; D001974:Bromosuccinimide / Q000494:pharmacology; D002417:Cattle; D003545:Cysteine; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006023:Glycoproteins / Q000378:metabolism*; D065089:Glycoside Hydrolase Inhibitors; D008321:Mammary Glands, Animal / Q000201:enzymology; D010658:Phenylglyoxal / Q000494:pharmacology; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D013329:Structure-Activity Relationship; D014364:Tryptophan; D000520:alpha-Glucosidases / Q000737:chemistry* / Q000378:metabolism*
D004791:Enzyme Inhibitors; D006023:Glycoproteins; D065089:Glycoside Hydrolase Inhibitors; D014364:Tryptophan; D001120:Arginine; C042059:glucosidase I; D000520:alpha-Glucosidases; D003545:Cysteine; D001974:Bromosuccinimide; D010658:Phenylglyoxal