Resolution of products of the duplicated hemoglobin alpha-chain loci by isoelectric focusing.

Using a high-resolution isoelectric focusing system, we have been able to separate the products of the individual "nonallelic+ mouse hemoglobin alpha-chain genes. The hemoglobins of mice of inbred strains that make two structurally different, but electrophoretically identical, alpha chains resolve into two bands on isoelectric focusing. The hemoglobin from other strains that make only one type of alpha chain forms a single band. Two new "alleles" of haplotypes of Hba (the alpha-chain complex locus) are described that code for hemoglobins with solubilities similar to that of the hemoglobin of strain C57BL/6J, but that give demonstrably different isoelectric focusing patterns. Because this method allows Hba typing of strains with the Hbbd or "diffuse" allele at the hemoglobin beta-chain locus, we have also been able to classify a number of previously untyped stocks, including some recently derived from feral populations. Among these mice we have found new representatives of most of the extant Hba genotypes. The demonstration that it is possible to detect genetic differences involving only neutral amino acid substitutions between proteins suggest that careful application of appropriate isoelectric focusing systems to the analysis of other proteins will greatly increase the sensitivity of our ability to detect genetic variation.