Primate epididymis-specific proteins: Characterization of ESC42, a novel protein containing a trefoil-like motif in monkey and human

Epididymal secreted proteins promote sperm maturation and fertilizing capac ity by interacting with sperm during passage through the epididymis. Here w e investigate the molecular basis of sperm maturation by isolating cDNA clo nes for novel epididymis-specific expressed sequences. Thirty-six novel cDN As were isolated and sequenced from a subtracted Macaca mulatta epididymis library. The clones encode proteins with a range of motifs characteristic o f protein-modifying enzymes, protease inhibitors, hydrophobic ligand-bindin g and transport proteins, extracellular matrix-interacting proteins, and tr anscription regulatory factors. The fall length coding sequences were obtai ned for 11 clones representing a range of abundance levels. Expression of e ach is regionally localized and androgen regulated. The most abundant, ESC4 2, contains a cysteine-rich region similar to the signature binding domain of the trefoil family of motogenic wound repair proteins. The monkey and hu man proteins are nearly 90% identical. Immunohistochemical staining reveale d that the protein is most abundant in the epithelium of the caput and is a lso present in the lumen and bound to sperm. The ESC42 gene, located on chr omosome 20q11, contains two exons encoding two nearly identical predicted s ignal peptides and a third exon encoding the rest of the protein.