Babino Alvaro, Tello Diana, Rojas Adriana, Bay Sylvie, Osinaga Eduardo, Alzari Pedro M
Departamento de Bioquimica, Facultad de Medicina, Av. Gral Flores 2125, Montevideo, Uruguay.
FEBS Lett. 2003 Feb 11;536(1-3):106-10. doi: 10.1016/s0014-5793(03)00037-1.
The structure of the tetrameric Vicia villosa isolectin B4 (VVLB4) in complex with a cancer antigen, the Tn glycopeptide (GalNAc-O-Ser), was determined at 2.7 A resolution. The N-acetylgalactoside moiety of the ligand binds to the primary combining site of VVLB4 in a similar way as observed for other Gal/GalNAc-specific plant lectins. The amino acid moiety of the Tn antigen is largely exposed to the solvent and makes few contacts with the protein. The structure of the complex provides a framework to understand the differences in the strength of VVLB4 binding to different sugars and emphasizes the role of a single protein residue, Tyr127, as a structural determinant of Tn-binding specificity.
以2.7埃的分辨率确定了四聚体野豌豆异凝集素B4（VVLB4）与癌症抗原Tn糖肽（GalNAc-O-Ser）复合物的结构。配体的N-乙酰半乳糖苷部分以与其他Gal/GalNAc特异性植物凝集素类似的方式结合到VVLB4的主要结合位点。Tn抗原的氨基酸部分大部分暴露于溶剂中，与蛋白质的接触很少。该复合物的结构为理解VVLB4与不同糖类结合强度的差异提供了一个框架，并强调了单个蛋白质残基Tyr127作为Tn结合特异性结构决定因素的作用。
