– Semenogelin-1 (SEMG1) is the predominant protein in semen; it is a secretory protein involved in the formation of a gel matrix entrapping the accessory gland secretions and ejaculated spermatozoa. The prostate-specific antigen (PSA) protease processes SEMG1 into smaller peptides, each possibly having a separate function. In the proteolysis process, Alpha-inhibin-92 and alpha-inhibin-31 are produced; they inhibit the secretion of pituitary follicle-stimulating hormone. At the same time, it breaks down the gel matrix, allowing the spermatozoa to move more freely.