Human type I hair keratin pseudogene phihHaA has functional orthologs in the chimpanzee and gorilla: evidence for recent inactivation of the human gene after the Pan-Homo divergence.

Bibliographic Collection: 
MOCA Reference, APE
Publication Type: Journal Article
Authors: Winter, H; Langbein, L; Krawczak, M; Cooper, D N; Jave-Suarez, L F; Rogers, M A; Praetzel, S; Heidt, P J; Schweizer, J
Year of Publication: 2001
Journal: Hum Genet
Volume: 108
Issue: 1
Pagination: 37-42
Date Published: 01/2001
Publication Language: eng
ISSN: 0340-6717
Keywords: Amino Acid Sequence, Animals, Bacterial Proteins, Base Sequence, DNA-Binding Proteins, Escherichia coli Proteins, Evolution, Molecular, Gene Expression, Gorilla gorilla, Humans, Keratins, Keratins, Hair-Specific, Keratins, Type I, Molecular Sequence Data, Multigene Family, Mutation, Pan troglodytes, Pseudogenes

In addition to nine functional genes, the human type I hair keratin gene cluster contains a pseudogene, phihHaA (KRTHAP1), which is thought to have been inactivated by a single base-pair substitution that introduced a premature TGA termination codon into exon 4. Large-scale genotyping of human, chimpanzee, and gorilla DNAs revealed the homozygous presence of the phihHaA nonsense mutation in humans of different ethnic backgrounds, but its absence in the functional orthologous chimpanzee (cHaA) and gorilla (gHaA) genes. Expression analyses of the encoded cHaA and gHaA hair keratins served to highlight dramatic differences between the hair keratin phenotypes of contemporary humans and the great apes. The relative numbers of synonymous and non-synonymous substitutions in the phihHaA and cHaA genes, as inferred by using the gHaA gene as an outgroup, suggest that the human hHaA gene was inactivated only recently, viz., less than 240,000 years ago. This implies that the hair keratin phenotype of hominids prior to this date, and after the Pan-Homo divergence some 5.5 million years ago, could have been identical to that of the great apes. In addition, the homozygous presence of the phihHaA exon 4 nonsense mutation in some of the earliest branching lineages among extant human populations lends strong support to the "single African origin" hypothesis of modern humans.

Alternate Journal: Hum. Genet.
Related MOCA Topics: