Characterization of AWN-1 glycosylated isoforms helps define the zona pellucida and serine proteinase inhibitor-binding region on boar spermadhesins.
Spermadhesin AWN-1 (14 kDa) belongs to a recently described family of boar sperm surface-associated proteins. AWN-1 is a multifunctional protein which possesses heparin-, serine proteinase inhibitor-, and zona pellucida glycoprotein-binding capability. Therefore it has been implicated in sperm capacitation and sperm-oocyte attachment. Here, we report the characterization of 22-25 kDa isoforms of AWN-1 isolated by heparin-affinity chromatography, which fail to bind to zona pellucida glycoproteins or serine proteinase inhibitors. Our results show that the structure of the high and low molecular mass AWN-1 forms differ in that the former is N-glycosylated at Asp50 and truncated at the C-terminus. The inability of the glycosylated AWN-1 molecules to bind ligands is due solely to the presence of the oligosaccharide moieties, however. This indicates that glycosylation of AWN-1 may modulate its ligand-binding capabilities. On the other hand, the effect of glycosylation on ligand-binding suggests that both the zona pellucida- and the serine proteinase inhibitor binding domain(s) may be located around the glycosylation point.
Calvete
J J
JJ
Institut für Reproduktionsmedizin, Tierärztliche Hochschule Hannover, Hannover-Kirchrode, Germany.
Sanz
L
L
Dostàlovà
Z
Z
Töpfer-Petersen
E
E
D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D015151:Immunoblotting; D008297:Male; D011485:Protein Binding; D011487:Protein Conformation; D029589:Seminal Plasma Proteins; D015842:Serine Proteinase Inhibitors / Q000378:metabolism*; D013094:Spermatozoa / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013552:Swine; D015044:Zona Pellucida / Q000378:metabolism*
D002352:Carrier Proteins; D029589:Seminal Plasma Proteins; D015842:Serine Proteinase Inhibitors; C425042:spermadhesin