Localization and structural characterization of an oligosaccharide O-linked to bovine PDC-109 Quantitation of the glycoprotein in seminal plasma and on the surface of ejaculated and capacitated spermatozoa

4 pags, 3 figs, 1 tabPDC-109 (13 kDa) is the most abundant component, and the major heparin-binding protein, of bovine (Bos taurus) seminal plasma. Here, we show that PDC-109 contains a single O-linked oligosaccharide (NeuNAcα(2-6)-Galβ(1-3)-GalNAc-) attached to Thr11. Immunoquantitation of PDC-109 indicates that its concentration in seminal plasma is 15-20 mg/ml. Though PDC-109 is not present on epididymal sperm, ejaculated spermatozoa on average are coated with (9.5 ± 0.3) × 106 molecules of PDC-109/cell. This value remained constant in swim-up sperm and decreased to (7.7 ± 0.4) × 106/spermatozoon after incubation for 24 h in capacitation medium at 39°C. These data substantiate the hypothesis that PDC-109 may be one of the seminal plasma components that enhance the fertilizing capacity of bull spermatozoa upon interaction with heparin-like glycosaminoglycans present in the female genital tract. © 1994.This work was financed by grants OlKY9103 from Bundesministerium für Forschung und Technologie (to E.T-P.) and PB92-0096 from the Dirección General de Investigación Científica y Técnica (J.J.C., A.R., and L.S.