Sunday, 18 November 2007

My project (3)

…ATP 7A and…
Gene map locus Xq12-q13
The ATP7A gene was cloned as a candidate for the site of mutations causing Menkes disease (MNK; 309400) by 3 independent groups (Vulpe et al., 1993; Chelly et al., 1993; Mercer et al., 1993). By a database search of the predicted sequence, Vulpe et al. (1993) found strong homology to P-type ATPases, a family of integral membrane proteins that use an aspartylphosphate intermediate to transport cations across membranes. The protein was found to have the characteristics of a copper-binding protein. Northern blot analysis showed that the mRNA of the gene, which was symbolized 'MNK' before its precise nature was known, is present in a variety of cell types and tissues, except liver, in which expression is reduced or absent. The findings were consistent with the clinical observation that the liver is largely unaffected in Menkes disease and fails to accumulate excess copper.
Levinson et al. (1994) and Mercer et al. (1994) isolated the mouse homolog of the Menkes disease gene. The mouse protein shows 89% identity to the human protein, and both proteins contain 8 transmembrane domains.

Tumer et al. (1995) determined that the ATP7A gene spans about 150 kb of genomic DNA and contains 23 exons. The ATG start codon is in the second exon. The ATP7A and ATP7B (606882) genes showed strikingly similar exonic structures, with almost identical structures starting from the fifth metal-binding domain, suggesting the presence of a common ancestor encoding 1, and possibly 2, metal-binding domains in addition to the ATPase 'core.'
Dierick et al. (1995) showed that the ATP7A gene contains 23 exons distributed over approximately 140 kb of genomic DNA. The authors showed that exon 10 is alternatively spliced. They found that the structures of the ATP7A and ATP7B genes are similar in the 3-prime two-thirds region, consistent with their common evolutionary ancestry.


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