This family contains the cytoplasmic domain of the Band 3 anion exchange proteins that exchange Cl-/HCO3-. Band 3 constitutes the most abundant polypeptide in the red blood cell membrane, comprising 25% of the total membrane protein. The cytoplasmic domain of band 3 functions primarily as an anchoring site for other membrane-associated proteins. Included among the protein ligands of cdb3 are ankyrin, protein 4.2, protein 4.1, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphofructokinase, aldolase, hemoglobin, hemichromes, and the protein tyrosine kinase (p72syk). [1]

1: Crystallographic structure and functional interpretation of the cytoplasmic domain of erythrocyte membrane band 3. Zhang D, Kiyatkin A, Bolin JT, Low PS; Blood 2000;96:2925-2933. PMID:11049968