Structural analysis of the Ss sialoglycoprotein specific for Henshaw blood group from human erythrocyte membranes.

The N-terminal structures of the MN and Ss erythrocyte membrane sialoglycoproteins (glycophorins A, B) from two Henshaw (He) blood-group heterozygotes were determined by manual sequencing of tryptic glycopeptides and various secondary fragments. No structural alteration of the MN glycoprotein could be detected. The He-specific portion of the Ss glycoprotein was found to exhibit the N-terminal sequence Trp-...-...-...-Gly- (+ =glycosylation). Thus it differs at three positions from its normal counterpart which possesses 'N' activity and exhibits the N-terminal structure Leu-...-...-...-Glu-. Analysis of the Ss glycoprotein from 15 He-negative erythrocyte samples did not reveal any of the three He-specific structural alterations. The presence of a glycine residue at the fifth position of the blood-group-M-active MN glycoprotein as well as in the He-specific Ss glycoprotein provides an explanation for the occurrence of antisera (anti-M^e) reacting with the M and He antigens. [ABSTRACT FROM AUTHOR]