Cysteine Rich PAK1 Inhibitor (CRIPAK)

CRIPAK is a negative regulator of PAK1 that is upregulated by estrogen. The predicted 446-amino acid protein contains an N-terminal C4 zinc finger domain, followed by 12 C3H zinc finger domains. Northern blot analysis detected wide expression of CRIPAK, with highest levels in trachea, prostate, and adrenal gland. RT-PCR revealed CRIPAK expression in all cancer cell lines examined.

Confocal microscopy of transfected breast cancer cells showed that CRIPAK had a predominant cytoplasmic and membrane localization; in some areas, CRIPAK partially colocalized with PAK1.Mutational analysis defined the binding regions as amino acids 132 to 270 of PAK1 and amino acids 367 to 446 of CRIPAK.