Epididymal Sperm Binding Protein 2 (ELSPBP2)

The deduced 133-amino acid protein contains an N-terminal signal sequence and 2 Fn2 domains separated by a 7-amino acid linker. A single free cysteine predicted to become the N-terminal residue following removal of the signal peptide may participate in intermolecular disulfide bridges. The deduced mature BPSH1 protein has 115 amino acids and a molecular mass of 13.8 kD. BSPH1 expression in epididymis and weak expression in testis, but no expression in prostate, seminal vesicles, brain, intestine, or lung. Database analysis revealed 3 Bsp homologs in mouse, only 2 of which appeared to be expressed, and a single Bsp homolog in chimpanzee and monkey. Bovine Bsp and its homologs share a high degree of conservation, particularly surrounding the cysteine residues.