Epididymal Sperm Binding Protein 1 (ELSPBP1)

The deduced 233-amino acid protein contains an N-terminal signal peptide characteristic of a secretory protein, and 4 tandem fibronectin type II (FN2) repeats. RT-PCR of epididymal cDNA suggested the presence of splice variants containing fewer FN2 modules. Human and canine proteins share nearly 80% identity. Northern blot analyses of both human and canine tissues revealed high levels of a 1.1-kb ELSPBP1 transcript only in epididymis, and not in other tissues investigated, including human testis, seminal vesicles, and prostate. Northern blot analysis of dissected human epididymis indicated expression in all regions, with highest expression in the corpus. In situ localization of Elspbp1 in canine epididymis indicated high expression along the basal surface of the duct epithelium, with strongest labeling of the distal caput and corpus epididymis.