Identification of a major secretory glycoprotein from rat epididymis: interaction with spermatozoa.
A polypeptide with molecular mass of 17 kDa has been partially purified and identified as a major secretory glycoprotein in the rat epididymis. It is phosphorylated and contains high mannose-type oligosaccharides with 5 and 6 mannose units predominantly. These sugar residues are sufficiently exposed in the molecule to be released by endo-beta-N-acetylglucosaminidase H without prior denaturation or protease digestion. Specific binding of the glycoprotein to testicular spermatozoa was demonstrated with Ka 0.2 x 10(9) M-1 and 17,200 sites per cell, while no binding to epididymal spermatozoa was detectable. Direct labeling of surface proteins on cauda epididymis spermatozoa revealed the presence of a major band of 16.2 kDa, which may be equivalent to GP17. The interaction of the epididymal secretory protein with sperm suggests a possible role in the maturation process.
Iusem
N D
ND
Instituto de Investigaciones Bioquimicas Fundacion Campomar, Buenos Aires, Argentina.
Pineiro
L
L
Blaquier
J A
JA
Belocopitow
E
E
D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D002845:Chromatography / Q000379:methods; D004586:Electrophoresis / Q000379:methods; D004822:Epididymis / Q000032:analysis* / Q000378:metabolism; D006023:Glycoproteins / Q000032:analysis / Q000302:isolation & purification* / Q000378:metabolism; D008297:Male; D008358:Mannose / Q000378:metabolism; D008970:Molecular Weight; D009844:Oligosaccharides; D011485:Protein Binding; D051381:Rats; D011919:Rats, Inbred Strains; D013094:Spermatozoa / Q000378:metabolism*; D014316:Tritium; D014415:Tunicamycin / Q000494:pharmacology
D006023:Glycoproteins; D009844:Oligosaccharides; D014316:Tritium; D014415:Tunicamycin; D008358:Mannose