Amino acid sequence of the blood group Mg-specific major human erythrocyte membrane sialoglycoprotein.

The structure of the N-terminal 21 residues of the blood group Mg-specific major human erythrocyte membrane sialoglycoprotein was investigated, using tryptic MgM peptides and secondary fragments prepared by staphylococcal V8 protease treatment. The sequence Leu-Ser-Thr-Asn-Glu was obtained for the N-terminal five residues. Therefore, the Mg gene appears to have evolved from a Thr leads to Asn mutation of an N allele. This alteration was found to prevent the glycosylation of the amino acids at the second and third positions.