title: Characterization of recombinant precursor proteins of the human seminal plasma sperm motility inhibitor synthesized in insect cells.
abstract: Human seminal plasma sperm motility inhibitor (SPMI) proteins which are exclusively secreted from seminal vesicles, inhibit sperm motility. It is secreted as biologically active 52 kDa and a mixture of 71 and 76 kDa precursor forms, which are identical to semenogelin-I and II (Sg-I and Sg-II), respectively. To understand the molecular mechanism underlying the inhibition of sperm motility by SPMI proteins, we expressed human Sg-I and Sg-II genes in insect cells using a baculovirus system. The baculoviruses expressing full-size Sg-I and Sg-II proteins that were N-terminally-tagged with a hexahistidine were selected, and were infected with Sf 21 cells. The Sg-I and Sg-II proteins were purified from infected cells by column chromatography using Ni-NTA resin 48 h after infection. The full-size Sg-I and Sg-II proteins were obtained in soluble forms. However, they tended to aggregate to form a gel, as expected from naturally occurring semenogelin. Both the purified recombinant Sg-I and Sg-II proteins showed strong SPMI activities with a complete inhibition of sperm motility at 60 units/mg, equivalent to the natural proteins. This production system that permits the generation of purified Sg-I and Sg-II proteins, as well as mutant derivatives, will be helpful for further study on male infertility.
authors.affiliation: Department of Urology, St. Marianna University School of Medicine, Kanagawa, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Murakami
authors.forename: M
authors.initials: M
authors.lastname: Yoshiike
authors.forename: M
authors.initials: M
authors.lastname: Satoh
authors.forename: Y
authors.initials: Y
authors.lastname: Furuichi
authors.forename: T
authors.initials: T
authors.lastname: Iwamoto
mesh_terms: D000818:Animals; D016367:Baculoviridae; D003429:Cross Reactions; D004926:Escherichia coli / Q000235:genetics; D012739:Gonadal Steroid Hormones / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007313:Insecta / Q000166:cytology / Q000235:genetics* / Q000821:virology; D008297:Male; D015202:Protein Engineering / Q000379:methods; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D029589:Seminal Plasma Proteins; D029607:Seminal Vesicle Secretory Proteins; D013094:Spermatozoa / Q000187:drug effects
chemical_list: D012739:Gonadal Steroid Hormones; D011994:Recombinant Proteins; D029589:Seminal Plasma Proteins; D029607:Seminal Vesicle Secretory Proteins; C424482:seminal vesicle-specific antigen