Complete amino acid sequence of the major early embryonic beta-like globin in chickens.

The rho globin is the major beta-like chain found in 5-day-old chick embryos. In association with two unique early embryonic alpha-like globins, it forms the two major hemoglobins of early chick development. This paper presents the complete amino acid sequence of the rho globin. There are no amino acid differences between the rho chain and the adult chicken beta chain at known Bohr effect or organophosphate-binding positions, and there are only 19 differences altogether. The rho globin ought to be functionally equivalent to the adult chicken beta globin. Since the adult and embryonic chains are very similar in sequence, they may be products of a relatively recent gene duplication in the chicken beta globin gene family. The possibility of a gene correction event is discussed.