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POLYCYSTIN AND SEA URCHIN REJ HOMOLOG-LIKE; PKDREJ

POLYCYSTIN AND SEA URCHIN REJ HOMOLOG-LIKE; PKDREJ

HGNC Approved Gene Symbol: PKDREJCytogenetic location: 22q13.31 Genomic coordinates (GRCh38): 22:46,255,662-46,263,342 (from NCBI)▼ Cloning and ExpressionBy ...

HGNC Approved Gene Symbol: PKDREJ

Cytogenetic location: 22q13.31 Genomic coordinates (GRCh38): 22:46,255,662-46,263,342 (from NCBI)

▼ Cloning and Expression
By searching cDNA and genomic databases for sequences similar to PKD1 (601313), PKD2 (173910), and the sea urchin sperm receptor for egg jelly (suREJ), Hughes et al. (1999) identified an intronless gene, which they designated PKDREJ, on cosmids located on chromosome 22q13. By screening a testis cDNA library, the authors obtained a PKDREJ cDNA encoding a deduced 2,253-amino acid protein. The PKDREJ protein is 64% identical and 78% similar to the mouse Pkdrej protein. Hydrophobicity analysis indicated that the structure of PKDREJ, with 11 transmembrane regions, is similar to that of PKD1. Northern blot analysis showed expression of an approximately 8-kb PKDREJ transcript exclusively in testis, coincident with the timing of sperm maturation.

▼ Mapping
By radiation hybrid analysis, Veldhuisen et al. (1999) mapped the PKDREJ gene to chromosome 22q13.3.

▼ Evolution
Sperm-egg interaction is a crucial step in fertilization, but the interacting sperm-egg proteins that mediate this process remained elusive. Rapid evolution of some fertilization proteins had been observed in a number of species, including evidence of positive selection in the evolution of components of the mammalian egg coat. The rapid evolution of the egg coat proteins could strongly select for changes on the sperm receptor, to maintain the interaction. Hamm et al. (2007) presented evidence that positive selection has driven the evolution of PKDREJ, a candidate sperm receptor of mammalian egg coat proteins. They sequenced PKDREJ from a panel of 14 primates, including humans, and conducted a comparative maximum-likelihood analysis of nucleotide changes and found evidence of positive selection. An additional panel of 48 humans were surveyed for nucleotide polymorphisms at the PKDREJ locus. The regions predicted to have been subject to adaptive evolution among primates showed several amino acid polymorphisms among humans. The distribution of polymorphisms suggested that balancing selection may maintain diverse PKDREJ alleles in some populations. Unknown was whether there are functional differences associated with these diverse alleles.

Tags: 22q13.31