The untranslated regions of beta-globin mRNA evolve at a functional rate in higher primates.

We have sequenced the 3' and 5' untranslated regions of beta-globin mRNAs from cebus monkey, rhesus monkey and chimpanzee. A comparison with the corresponding human sequences reveals that the rate of sequence divergence among the higher primates is the same in the 3' and 5' noncoding regions and that this rate is several times lower than the rate for silent substitutions in the coding regions. In addition, the rate of sequence divergence in the 3' untranslated region of the primate beta-globin nRNA is several times lower than the rate calculated for this region from other comparisons. The low rate of sequence divergence in the noncoding 3' end of the primate beta-globin mRNAs may indicate a specialized and significant function for this region in the higher primates.