The use of monoclonal antibodies to quantify the levels of sialoglycoproteins α and δ and variant sialoglycoproteins in human erythrocyte membranes

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Abstract
1. By using radioiodinated monoclonal antibodies we have estimated that there are about 600000 copies of sialoglycoprotein .alpha. (synonym glycophorin A) and 80,000 copies of sialoglycoprotein .delta. (synonym glycophorin B) per normal human erythrocyte. 2. Erythrocytes expressing the product of only one .alpha. gene contain about 300,000 copies of .alpha./cell. 3. Two erythrocyte types containing .alpha.-.delta. hybrid molecules were studied. Those with heterozygous expression of the (.alpha.-.delta.)Mi.V gene contain about 100,000 .alpha.-.delta. copies per cell, whereas those with heterozygous expression of the En(UK) gene contain about 80,000 .alpha.-.delta. copies/cell. 4. Erythrocytes types containing .delta.-.alpha. hybrid molecules were also studied. About 200,000 copies of (.delta.-.alpha.)Dantu were measured in cells with heterozygous expression of the (.delta.-.alpha.)Dantu gene (donor M.P.), whereas about 315,000 copies of the putative (.delta.-.alpha.)Dantu hybrid were found on the erythrocytes of donor J. O. [which also have heterozygous expression of the putative (.delta.-.alpha.)Dantu gene]. 5. The erythrocytes of donor M. P. have normal levels of .alpha., whereas those of donor J. O. have only about half-normal levels. It is proposed that the hybrid sialoglycoprotein of donor J. O. is of .alpha.-.delta.-.alpha. composition [(.alpha.-.delta.-.alpha.)Dantu] rather than .delta.-.alpha. and results from a double cross-over analogous to that which gives rise to haemoglobin Parchman.