Semenogelin I: a coagulum forming, multifunctional seminal vesicle protein
- Cite this article as:
- Robert, M. & Gagnon, C. CMLS, Cell. Mol. Life Sci. (1999) 55: 944. doi:10.1007/s000180050346
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Human seminal plasma spontaneously coagulates after ejaculation. The major component of this coagulum is semenogelin I, a 52-kDa protein expressed exclusively in the seminal vesicles. Recently, a sperm motility inhibitor has been found to be identical to semenogelin I, suggesting that it may also be a physiological sperm motility inhibitor. The protein is rapidly cleaved after ejaculation by the chymotrypsin-like prostatic protease prostate-specific antigen, resulting in liquefaction of the semen coagulum and the progressive release of motile spermatozoa. Some of the cleavage products of Sg I may also have various biological functions. While the semenogelin I protein is unique to human and higher primates, it has recently been shown to belong to a gene family having a similar gene structure but encoding widely differing proteins. The recently elucidated characteristics of the semenogelin I gene as well as the biochemical and functional properties of the encoded protein are reviewed, and an attempt is made to integrate the various findings into a model for semen coagulation, sperm immobilization and potential other functions.