Semenogelin I: a coagulum forming, multifunctional seminal vesicle protein.
Human seminal plasma spontaneously coagulates after ejaculation. The major component of this coagulum is semenogelin 1, 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.
Chugai Research Institute for Molecular Medicine, Inc., Ibaraki, Japan.
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Robert
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Gagnon
D000595:Amino Acid Sequence; D000818:Animals; D005786:Gene Expression Regulation; D005796:Genes; D012739:Gonadal Steroid Hormones / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009928:Organ Specificity; D017430:Prostate-Specific Antigen / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D012661:Semen / Q000737:chemistry / Q000502:physiology; D029589:Seminal Plasma Proteins; D029607:Seminal Vesicle Secretory Proteins; D012669:Seminal Vesicles / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000378:metabolism; D013081:Sperm Motility; D015032:Zinc / Q000502:physiology
D012739:Gonadal Steroid Hormones; D011506:Proteins; D029589:Seminal Plasma Proteins; D029607:Seminal Vesicle Secretory Proteins; C424482:seminal vesicle-specific antigen; D012697:Serine Endopeptidases; D017430:Prostate-Specific Antigen; D015032:Zinc