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-han d domains which is identical to FKBP6/65 in overall structural organization . However, the two proteins share only 66% amino acid identity. FKBP9 is ex pressed at high levels in mouse heart, muscle, lung, and kidney. While FKBP 6 was previously mapped to chromosome 11, the Fkbp9 gene was mapped to mous e chromosome 6 by analysis of a multilocus cross. These results identify a new member of the mouse FKBP protein family located on a separate chromosom e.