Quantitation of hemoglobin α chains in adult and fetal goats; gene duplication and the production of polypeptide chains

The relative amounts of three hemoglobin α chains, the I α, II α, and I α B chains have been determined in normal adult, fetal and newborn goats, in goats with a heterozygosity for the Hb β D or the Hb I α B allele, and in goats with a homozygosity for the Hb I α B allele. Several animals were studied when the β A (and β D) chains were in part or almost completely replaced by the β C chain, which is the product of a dormant gene. The data indicate: 1. 1. An increase in the relative and absolute amounts of II α chains in adult and newborn goats in the presence of the Hb I α B allele; this increase was about 15% for the adult heterozygous AB goat, and about 32% for the adult homozygous BB goat. 2. 2. The relative amounts of the three α chains are not altered when the β A production is (partially) replaced by that of the β D or β C chains. 3. 3. The percentages of I α B chains in the newborn AB and BB goats are significantly higher than those observed in the corresponding adult goats; this increase is accompanied by a corresponding decrease in the percentages of the II α chain and probably not of the I α chain. The observed changes were found to be more or less directly related to the amount of fetal hemoglobin present in the blood samples. These observations have been interpreted to mean that a certain selective preference of non-α polypeptide chains for specific α polypeptide chains to form dimer subunits may be of importance for the control of the rate of synthesis of hemoglobin molecules in addition to control mechanisms at the gene or ribosome level.