Semenogelin (SEMG)

Semenogelins, primarily Semenogelin-1 (SEMG1) and Semenogelin-2 (SEMG2), are the predominant proteins involved in the formation of the human seminal coagulum (UniProt P04279, P08107). Secreted by the seminal vesicles, these proteins undergo rapid gelation upon ejaculation, creating a physical matrix that traps spermatozoa and protects them within the female reproductive tract (de Lamirande, 2007). The subsequent liquefaction of this coagulum is a critical step for fertility, facilitated by the proteolytic activity of Prostate-Specific Antigen (PSA/KLK3), which cleaves the semenogelins into smaller fragments (Robert et al., 2002). Beyond their structural role, semenogelins are involved in inhibiting sperm motility, binding zinc ions, and exerting antimicrobial effects (Jonsson et al., 2005). In clinical medicine, failure of the coagulum to liquefy—often due to PSA dysfunction or semenogelin mutations—is a recognized cause of male infertility (hyperviscosity). These proteins are also significant in forensic science as definitive markers for the presence of semen and are being investigated as potential targets for non-hormonal male contraceptives (Lundwall et al., 2002).

Other names

Semenogelin-1Semenogelin-2SEMG1SEMG2Seminal basic proteinSGISGIISeminal coagulum proteins

Semenogelins form a gel-like matrix through zinc-dependent interactions; this matrix is subsequently degraded by the serine protease Prostate-specific antigen (PSA), which cleaves the proteins at specific sites to release sperm (Robert et al., 2002).