A protein containing 131 amino acids that is encoded by the GYPA gene. It spans the plasma membrane of the human red blood cell once and presents its amino terminal end to the extracellular surface. There are two polymorphic versions of glycophorin A in humans. The only differences are at positions 1 and 5 in the extracellular portion of the molecule. The M antigen contains serine and glycine at positions 1 and 5 in the chain, while the N antigen has leucine and glutamic acid at these positions. See MN blood groups.
Subjects: Genetics and Genomics.