Structural Evidence for Heterogeneity of Two Hemoglobin α Chain Gene Loci in White-tailed Deer

• Published in: The Journal of biological chemistry 1972-11, Vol.247 (22), p.7320-7324
• Main Authors: Taylor, W. Jape, Easley, Caroline W., Kitchen, Hyram
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)44632-2

An examination by tryptic peptide mapping and partial sequence determination of critical peptides of hemoglobins from white-tailed deer of known parentage established the presence of from one to three α chains in individual animals. Variations in the deer α chains occur at amino acid position number 20, at which iiα1 contains lysine while iα3 and iα3′ contain aspartic acid, and at position number 24, at which phenylalanine appears in iiα1 and iα3′ and tyrosine appears in iα3. Either the iα3′ or the iα3 chain may appear alone, but the iiα1 chain is always linked with iα3′. Duplication of a structural gene for the iα3′ chain, followed by a mutation at position number 20 to produce the iiα1 gene, and a simple point mutation in the iα3′ gene at position number 24 to produce the iα3 gene explain the findings with the smallest number of separate genetic events. The lysine-aspartic acid substitution in the duplicated gene product is less conservative than the phenylalanine-tyrosine mutation, supporting the theoretical concept that gene duplication permits a greater degree of evolutionary experimentation. Interestingly, the nonduplicated gene continues to persist singly in the population as well as in association with its mutant duplicate. This finding supports the concept that heterogeneity of the α chain gene loci may exist in man as well.