The involucrin gene of the owl monkey: origin of the early region.

A large part of the coding region of the hominoid involucrin gene is of recent origin. This part of the gene, which we have called the modern segment, contains numerous repeats of a sequence of 10 codons, created by multiple duplications some of which consist of 3-12 repeats. We have sequenced two alleles of the involucrin gene in the owl monkey and found that the involucrin gene of this species also possesses a modern segment. By comparing the modern segment of the owl monkey with that of the hominoids, we find that only a part of this segment is shared by the two species. We call this part the early region because it must have originated in a common ancestor of the anthropoids. The rest of the hominoid modern segment does not correspond to any groups of repeats in the owl monkey and was therefore created after divergence of the two lineages. As in the hominoids, the latest additions to the modern segment of the owl monkey have been in its 5' half, which possesses different duplication patterns in the two alleles. Lineage divergences within the anthropoids can be detected at different sites within the modern segment.