The nucleotide sequence of the major beta-globin mRNA from Xenopus laevis.

The nucleotide sequence of a cloned fragment containing an almost complete copy of the mRNA encoding the major adult beta-globin polypeptide in Xenopus laevis, the South African Clawed Toad, is presented. A procedure for strand separation by hybridization to complementary mRNA was used to determine some of the sequence and this technique is described. The complete amino acid sequence of the polypeptide has been deduced and comparison with other vertebrate beta-globins reveals several highly conserved, and therefore potentially important, regions of the protein. The sequence of beta-globin mRNA has been determined in several mammals, and in the chicken. Thus we have searched for conserved regions in the non-coding portions of these mRNA sequences, which encode the same protein, but which have been evolving separately for several hundred million years.