A novel fatty acid-binding protein (FABP) gene resulting from tandem gene duplication in mammals: transcription in rat retina and testis.

We have identified a new member of the FABP gene family, designated FABP12. FABP12 has the same structure as other FABP genes and resides in a cluster with FABP4/5/8/9 within 300,000 bp chromosomal region. FABP12 orthologs are found in mammals, but not in the zebrafish or chicken genomes. We demonstrate that FABP12 is expressed in rodent retina and testis, as well as in human retinoblastoma cell lines. In situ hybridization of adult rat retinal tissue indicates that FABP12 mRNA is expressed in ganglion and inner nuclear layer cells. Analysis of adult rat testis reveals a pattern of expression that is different from that of the known testis FABP (FABP9) in the testicular germ cells, suggesting distinct roles for these two genes during mammalian spermatogenesis. We propose that FABP12 arose as the result of tandem gene duplication, a mechanism that may have been instrumental to the expansion of the FABP family.