Rac-GTPase Activating Protein 1 (RACGAP1)

The predicted 527-amino acid RACGAP1 protein has a large N-terminal region containing a protein kinase C -like cysteine-rich motif. The authors determined that RACGAP1 shares highest homology with the Drosophila RnRacGAP and the chimerins of rat and human. Functional analysis showed that the GAP domain of RACGAP1 exhibits strong GAP activity towards CDC42, RAC1, and RAC2. Northern blot analysis detected an approximately 3.2-kb RACGAP1 transcript that was most abundantly expressed in testis, with low expression in most other tissues. Western blot analysis detected a RACGAP1 protein of 58 kD in testis extracts. In situ hybridization showed that RACGAP1 expression is restricted to germ cells in mature testis.