Peptidylprolyl Isomerase G (PPIG)

PPIG is predicted to encode a 754-amino acid protein containing 2 Nopp140 (nucleolar phosphoprotein of 140 kD)-related domains and a large C-terminal serine/arginine (SR)-rich domain found predominantly in pre-mRNA splicing factors. The N-terminal region of PPIG contains a peptidyl-prolyl cis-trans isomerase domain characteristic of immunophilins/cyclophilins. PPIG shares 37.8% sequence identity with NKTR, a myeloid-specific nuclear protein. By Northern blot analysis, Nestel et al. (1996) detected PPIG expression at similar levels in lung, liver, kidney, small intestine, testis, and brain. They detected major 4-kb and minor 10-kb PPIG transcripts in human B-cell RNA. Although PPIG was widely expressed, it appeared to be absent from NK cells.