Identification of two putative novel folate receptor genes in humans and mouse.

Utilizing a 'database mining' strategy to detect novel folate receptors (FR), we identified two potential novel members in the mouse and human. The mouse gene (Folbp3) was sequenced and found to predict a 28.2 kDa protein that consists of 244 amino acids that is highly expressed in both the thymus and spleen, suggesting a potential role in the immune system. The human gene (FR-delta) is mapped to chromosome 11q14, and predicts a 27.7 kDa protein that is comprised of 241 amino acids. However, expression of the human gene was not detected in 59 samples from both adult and embryonic tissue sources, suggesting a highly restricted spatial/temporal expression pattern, an alternatively spliced variant or an additional FR pseudogene. Using T31 mouse radiation hybrid mapping, Folbp3 was mapped to a region on mouse chromosome 9 that is syntenic to human chromosome 19p13. As the chromosomal locations of Folbp1 murine and Folbp2 genes were previously unknown, we utilized the same approach and mapped both genes to a region of mouse chromosome 7 that is syntenic to the human FR loci on chromosome 11q13.