Amino acid sequence and attachment sites of oligosaccharide units of porcine erythrocyte glycophorin.

The amino acid sequence of the glycophorin from porcine erythrocyte membrane has been determined by Edman degradation. Porcine glycophorin is a polypeptide chain of 133 amino acid residues and contains 12 oligosaccharide units attached to the amino-terminal side of the molecule. Ten oligosaccharides are linked O-glycosidically to threonine/serine residues and the remaining two oligosaccharides are attached N-glycosidically to asparagine residues. The amino acid sequence is consistent with the transmembrane orientation of glycophorin. Porcine and human glycophorins are similar in amphiphilic property, molecular size, and carbohydrate content, but the two glycophorins differ considerably in the amino acid sequence: particularly, the amino-terminal sequences which are highly glycosylated show no homology.