Identification and genetic mapping of the mouse Fkbp9 gene encoding a new member of FK506-binding protein family

We have isolated a gene from a cDNA library generated from the thymus of a mouse with severe combined immune deficiency, termed FKBP9, that encodes a protein related to FK506-binding protein 6 (65 kDa, FKBP65). FKBP9 contains four peptidyl-prolyl cis-trans isomerase (PPIase) signature and two EF-hand domains which is identical to FKBP6/65 in overall structural organization. However, the two proteins share only 66% amino acid identity. FKBP9 is expressed at high levels in mouse heart, muscle, lung, and kidney. While FKBP6 was previously mapped to chromosome 11, the Fkbp9 gene was mapped to mouse chromosome 6 by analysis of a multilocus cross. These results identify a new member of the mouse FKBP protein family located on a separate chromosome.