8.A.168. The Glycophorin (GP) Family
Glycophorin A is the major intrinsic membrane protein of the erythrocyte (Blanchard 1990). The N-terminal glycosylated segment, which lies outside the erythrocyte membrane, has MN blood group receptor function (Altable and de la Serna 2021). This protein is important for the function of SLC4A1 (the anion exchanger (AE, HCO3-:Cl- antiporter; also called Band 3, see TC# 2.A.31.1.1) and is required for high activity of SLC4A1. GP may be involved in translocation of SLC4A1 to the plasma membrane (Cartron and Rahuel 1992, . It is a receptor for influenza virus and Hepatitis A virus, and it is a receptor for Plasmodium falciparum erythrocyte-binding antigen 175 (EBA-175) (see TC# 9.B.367.1.4); binding of EBA-175 is dependent on sialic acid residues of the O-linked glycans. Almost the entire populations of four transmembrane proteins, including glycophorin A, Band 2 (AI) and other erythrocyte membrane proteins, are immobilized by either the incorporation within large multiprotein complexes or entrapment within the protein network of the cortical spectrin cytoskeleton, preventing lateral diffusion (Kodippili et al. 2020).