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Evolutionary History of Sex Linked Mammalian Amelogenin Genes
Translocation of the amelogenin alleles to what became
the sex chromosomes is explored by Iwase et al.
(Graduate University for Advanced Studies, Sokendai, Japan)
in the third paper, Evolutionary History of Sex-
Linked Mammalian Amelogenin Genes. Amelogenin
represents about 90% of the protein in developing dental
enamel. The amelogenin gene translocated out of the
SCPP cluster and into the first intron of ARHGAP6 (Rho
GTPase-activating protein 6 gene) on another autosomal
chromosome. In the ancestral lineage of eutherian (placental)
mammals, the pair of homologous autosomes encoding
AMEL translocated and became the short arms of
the sex chromosomes. The amelogenin genes first resided
in the autosomal-like (pseudoautosomal) region of the
sex chromosomes, and then came to straddle the pseudoautosomal
boundary. For some time, only the AMEL region
downstream of intron 2 could undergo homologous
recombination. The AMEL 5 region (upstream from
transposon MER5 in intron 2) differentiated before the
eutherian radiation, while the 3 region (downstream
from MER5) differentiated independently within individual
eutherian orders. Because of its recent history, the
amelogenin genes on the X and Y chromosomes are used
in PCR analyses to determine gender in forensics and archeology.
Source:
- Molecular Evolution and Genetic Defects of Teeth, Cells Tissues Organs, 2007