Specific localization in the equatorial region of gp20, a 20 kDa sialylglycoprotein of the capacitated human spermatozoon acquired during epididymal transit which is necessary to penetrate zona-free hamster eggs.
In this study we set out to characterize gp20, a 20 kDa glycoprotein of the human sperm surface, first identified by us by radiolabelling the sialic acid residues of the sperm surface [R. Focarelli et al. (1995), Mol. Hum. Reprod., 2, 2755-2759]. The protein was partially purified from pooled sperm samples of several healthy donors and used to raise a specific antiserum to study its localization in the reproductive system. When tested with freshly ejaculated spermatozoa, the anti-gp20 antibody intensely stained the head and midpiece. However, on capacitated spermatozoa the antigen was restricted to a sharp zone in the equatorial region. The antibody did not bind to differentiating germ cells but the antigen was present in epididymal epithelial cells and also in seminal plasma. Anti-gp20 exerted a blocking effect in a test for sperm penetration of zona-free hamster eggs, thus suggesting that gp20 is involved in the early stages of fertilization.
Focarelli
R
R
Department of Evolutionary Biology, University of Siena, Italy.
Giuffrida
A
A
Capparelli
S
S
Scibona
M
M
Menchini Fabris
F
F
Francavilla
F
F
Francavilla
S
S
Giovampaola
C D
CD
Rosati
F
F
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D004822:Epididymis / Q000737:chemistry* / Q000502:physiology; D005260:Female; D006801:Humans; D007106:Immune Sera; D066298:In Vitro Techniques; D008297:Male; D008970:Molecular Weight; D012795:Sialoglycoproteins / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification; D013075:Sperm Capacitation; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000737:chemistry* / Q000502:physiology
D007106:Immune Sera; D012795:Sialoglycoproteins