Eppin: an epididymal protease inhibitor and a target for male contraception.

Eppin (epididymal protease inhibitor) is one of several serine protease (or serine protease-like) inhibitors that are encoded by genes on human chromosome 20 and on mouse chromosome 2. Here we review our current knowledge of human and mouse Eppin genes and the Eppin protein in the context of protease inhibitors. Antibodies to Eppin in immunized male monkeys provide an effective and reversible contraceptive and these antibodies may be effective by interfering with Eppin's interaction with semenogelin during ejaculation. We review Eppin-semenogelin interaction and present a working model in the context of the hydrolysis of semenogelin by prostate specific antigen.