Abstract We describe the cloning and expression of cDNAs encoding a novel human protein of 208 amino acid residues with a predicted molecular mass of 22.6 kDa and its mouse homologue. We name this protein as AWP1 ( a ssociated w ith P RK 1) . AWP1 is a ubiquitously expressed protein, and the Awp1 gene is switched on during early human and mouse development. When expressed in COS-1 cells, the Myc-tagged AWP1 has an apparent molecular mass higher than that deduced from its amino acid sequence. AWP1 possesses a conserved zf-A20 zinc finger domain at its N-terminal and a zf-AN1 zinc finger domain at its C-terminal. Co-immunoprecipitation experiments revealed that mouse AWP1 specifically interacts with a rat serine/threonine protein kinase PRK1 in vivo. Hence, AWP1 may play a regulatory role in mammalian signal transduction pathways.