Carboxypeptidase X1 (CPX1)

CPX1 is a member of the M14 family of zinc carboxypeptidases; however, the protein has no detectable carboxypeptidase activity. The encoded protein is thought to be an extracellular and/or membrane protein, and may be involved in cell-cell interactions.The deduced 722-amino acid protein has a calculated molecular mass of 79 kD. Cpx1 contains an N-terminal discoidin domain and a C-terminal carboxypeptidase domain that includes a putative calcium-binding region but lacks several residues important for catalytic activity in other carboxypeptidases. Northern blot analysis detected a 2.5-kb transcript in most tissues examined, with highest levels in testis and spleen, moderate levels in salivary gland, brain, heart, lung, and kidney, and low levels in liver and muscle.