The human PIN1 peptidyl-prolyl cis/trans isomerase gene maps to human chromosome 19p13 and the closely related PIN1L gene to 1p31.

The human PIN1 gene encodes an essential nuclear peptidyl-prolyl cis/trans isomerase involved in the regulation of mitosis. PIN1 is a member of a new class of peptidyl-prolyl cis/trans isomerases that includes the Escherichia coli parvulin, yeast ESS1, and Drosophila melanogaster dodo gene products. Analysis of human ESTs showed that there are two different but closely related human transcripts, one of which corresponds to PIN1. Gene localization, using both FISH and tritium-labeled probes, showed that each of the human transcripts hybridized to 1p31 and 19p13. Primers were designed to discriminate between the two transcripts, and PCR on DNA from hamster/human somatic cell hybrids retaining chromosomes 1 or 19 was used to map the human PIN1 gene to chromosome 19, and PIN1L, a closely related gene, to chromosome 1. The results establish that PIN1 is at 19p13 and PIN1L at 1p31. PCR was used to clone the coding region for PIN1L. The PIN1L cDNA is 89% identical at the nucleotide level to the PIN1 transcript, but contains a shift in the reading frame. It encodes a 100-amino-acid variant protein consisting of 63 amino acids homologous (90% identical) to PIN1 and containing the entire WW domain, fused to a 37-amino-acid tail. The protein encoded by PIN1L may have some functional role or alternatively PIN1L may be a transcribed pseudogene.