X-Ray Radiation Resistance Associated Protein 1 (XRRA1)

The human XRRA1 gene encodes a deduced 559-amino acid protein with 2 possible sites of leucine-rich repeats, a PEST sequence, 2 tyrosine phosphorylation sites, and bipartite nuclear targeting sequences. XRRA1 gene appears to be highly conserved among mammals. RT-PCR detected the human XRRA1 transcript predominantly in testis, prostate, and ovary, and at variable levels in all cancer cell lines tested. DNA microarray analysis revealed a 3-fold greater expression of XRRA1 in macaque testis compared to mixed tissues, and similar levels of expression in macaque and human testis. Overexpression of a GFP-XRRA1 construct in HCT116 cells and COS-7 cells resulted in only transient expression, suggesting that levels of XRRA1 above the basal level may be lethal to cells. XRRA1 localized to the nucleus and cytoplasm of transfected cells.