The Structure of a Phytohemagglutinin Receptor Site from Human Erythrocytes

作者：Rosalind Kornfeld, Stuart A. Kornfeld · 发表于：Journal of Biological Chemistry · 年份：1970 · DOI：10.1016/s0021-9258(18)63104-7 · 被引用次数：348 · 研究领域：Carbohydrate Chemistry and Synthesis、Toxin Mechanisms and Immunotoxins、Glycosylation and Glycoproteins Research

A highly purified glycopeptide with potent phytohemagglutinin (PHA) receptor site activity has been isolated from human erythrocyte membranes. The glycopeptide was released from the membranes by trypsin, treated with alkaline borohydride, and purified by repeated gel filtration, further proteolytic digestion with Pronase, and diethylaminoethyl cellulose chromatography. It has a molecular weight of approximately 2000 and the following composition (in residues): sialic acid, 1; galactose, 2; mannose, 2; N-acetylglucosamine, 3; aspartic acid, 1.5; serine, 1; and threonine, 1. The sequence of the carbohydrate residues in the oligosaccharide chain was determined by sequential cleavage of the sugars from the nonreducing end with specific glycosidases. The glycopeptide has a single branched oligosaccharide chain containing two nonreducing termini, one with the composition galactose (β)/→ N-acetylglucosamine and the other with sialic acid → galactose (β)/→ N-acetylglucosamine. Each branch is connected to the inner core which contains 2 mannose and 1 N-acetylglucosamine residues. Since the oligosaccharide chain was not released from the trypsin fragment during the alkaline borohydride treatment, it is probably linked to the peptide backbone by an N-acetylglucosaminylasparagine linkage. Removal of the sialic acid residue does not affect PHA-inhibitory activity. When the galactose residues are removed, 90% of the PHA-inhibitory activity is lost. Model compounds having the terminal seque...