Blood Group‐Active Surface Molecules of the Human Red Blood Cell

Abstract

Abstract. The surface of the human red blood cell is dominated by a small number of abundant blood group active proteins. The major proteins are the anion transport protein (band 3) which has AB(H) activity, and Glycophorin A which has MN activity. Band 3 and Glycophorin A are of equal abundance in the normal red cell membrane (approximately lo6 copies of each) and the two proteins may associate together as a complex. The glucose transporter (band 4.5) has AB(H) activity and there are about 5 x lo5 copiedred cell. Several polypeptides associate together to form the Rh complex. The major components of this complex (abundance 1-2 x lo5 copieshed cell) are polypeptides of M, 30,000, polypeptides of MI 45,000-100,000 and Glycophorin B. The antigens of the Rh blood group system appear to be associated with the polypeptides of M, 30,000 and those of M, 45,000-100,000 (the latter also express AB(H) activity). Glycophorin B expresses the blood group 'N' antigen and the Ss antigens. Glycophorins C and D carry the Gerbich antigens and, together, these polypeptides comprise approximately lo5 copiedred cell. The complete protein sequence of all the above-mentioned proteins is known, except for the MI 30,000 and M, 45,000-100,000 polypeptides of the Rh complex for which only partial sequences are available, and Glycophorin D, the sequence of which can be inferred from that of Glycophorin C . Several of the minor blood group active proteins at the red cell surface (abundance 4 . 2 x 104/red cell) have been the subject of recent studies. The polypeptide expressing Cromer-related blood group antigens has been identified as decay-accelerating factor and that carrying the Ina/Inb antigens as CD44. The protein sequence of both of these proteins has been deduced form nucleotide sequencing. The polypeptides expressing Kell antigens, Lutheran antigens, Fy antigens, and LW antigens have also been identified and partially characterised.

Other Blood Group Antigens and Antibodies

“…LU encodes the Lutheran (Lu) glycoprotein and a spliced form of the glycoprotein, basal cell adhesion molecule (B-CAM). 39,40 The minor isoform (B-CAM) has an approximate M r of 78,000, because it lacks the cytoplasmic tail and has an increased expression on epithelial cancer cells. 37 The protein is predicted to have five disulfide-bonded, extracellular, Ig superfamily (IgSF) domains (two variable-region and three constant-region sets).…”

Histochemical analysis of blood group antigens in human sublingual glands and pancreas. An application of high-performance liquid chromatography to estimate the quantity of galactose liberated from tissue sections by ?-galactosidase digestion

“…An extremely high concentration of B antigen sites in the mucous cells of sublingual glands indicates that many oligosaccharide side-chains in a core protein are decorated by B antigens. This is a quite different situation from the red blood cells in which each glycoprotein carrying ABH antigens has a single branched or unbranched poly-N-acetyllactosaminyl N-glycosidically linked oligosaccharide with the antigen at its non-reducing termini (Anstee, 1990). Harpaz et al (1975) reported that the B antigenic sites on AB erythrocytes are about onehalf the number of those on B erythrocytes.…”

Rh, Kell, Duffy, and Kidd Antigens and Antibodies

“…109,110 Transient depression of Kell system antigens has been associated with the presence of autoantibodies mimicking alloantibodies in autoimmune hemolytic anemia and with microbial infections. The gene, which has only two deleted (some Gerbich-negative phenotypes).…”