Topology of bovine red cell antigens as a function of the organization of their genes

Abstract

Bovine erythrocytes from genetically defined animals were examined by electron microscopy for cell surface distribution of their antigens as a function of the organization of genes coding for the antigens. No blocking or inhibition of labeling was found when cells were double-labeled for two antigens whose genes resided in a) cis or trans conformations within the same blood group system (R2 and W antigens of the C system), or b) in different blood group systems (R2 and Z antigens of theC and Z systems, respectively). The results suggest that these antigens are probably distinct moieties on the cell surface rather than a series of determinants on a common backbone macromolecule. Genes coding for these antigens are, therefore, probably arranged in the genome as separate but closely linked genes and not as a series of multiple alleles, each allele coding for several serological determinants. A nonreciprocal increase in labeled sites was found on labeling two particular antigens within the same blood group system (R2 and X2 antigens of the C system). By absorption a parallel serological effect was also found for this pair of antigens.