Calvete J J, Sanz L, Dostàlovà Z, Töpfer-Petersen E
Institut für Reproduktionsmedizin, Tierärztliche Hochschule Hannover, Hannover-Kirchrode, Germany.
FEBS Lett. 1993 Nov 8;334(1):37-40. doi: 10.1016/0014-5793(93)81675-p.
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.
精子黏附素AWN-1（14 kDa）属于最近描述的猪精子表面相关蛋白家族。AWN-1是一种多功能蛋白，具有与肝素、丝氨酸蛋白酶抑制剂和透明带糖蛋白结合的能力。因此，它与精子获能和精卵结合有关。在此，我们报道了通过肝素亲和层析分离得到的22 - 25 kDa的AWN-1同工型的特性，这些同工型不能与透明带糖蛋白或丝氨酸蛋白酶抑制剂结合。我们的结果表明，高分子量和低分子量的AWN-1形式的结构不同，前者在Asp50处进行N-糖基化，在C端被截断。然而，糖基化的AWN-1分子无法结合配体仅仅是由于寡糖部分的存在。这表明AWN-1的糖基化可能调节其配体结合能力。另一方面，糖基化对配体结合的影响表明，透明带和丝氨酸蛋白酶抑制剂结合结构域可能位于糖基化点周围。
