Department of Biochemistry and Cellular and Molecular Biology, M407 Walters Life Science Building, University of Tennessee, Knoxville, Tennessee 37996, USA.
Trends Cardiovasc Med. 1998 Apr;8(3):124-31. doi: 10.1016/S1050-1738(97)00136-9.
A previously accepted model for the morphoregulatory activity of vitronectin is based on the idea that the heparin-binding site is buried within the circulating, monomeric form of vitronectin and that it is exposed on conversion to the multimeric form by denaturation or incorporation into the extracellular matrix. New evidence indicates that the heparin-binding sites are similarly exposed in the two forms of vitronectin and supports an alternative model for apparently altered heparin affinity. Differences in the heparin-binding properties of circulating and matrix-associated vitronectin result from an increased number of binding sites on the multivalent matrix form. By analogy with other instances in which multivalent binding interactions increase functional affinity for carbohydrates or lectins, the self-association of vitronectin into a multimeric form allows effective neutralization of heparin at the endothelial surface in the vicinity of a thrombus.
先前提出的关于 vitronectin 的形态调节活性的模型基于以下观点：肝素结合位点存在于循环的单体形式的 vitronectin 中，并且当它通过变性或整合到细胞外基质中转化为多聚体形式时暴露出来。新的证据表明，肝素结合位点在 vitronectin 的两种形式中都同样暴露，并支持了肝素亲和力明显改变的替代模型。循环和基质相关 vitronectin 的肝素结合特性的差异源于多价基质形式上结合位点数量的增加。通过与其他多价结合相互作用增加碳水化合物或凝集素功能亲和力的实例类似，vitronectin 自身缔合成多聚体形式允许在血栓附近的内皮表面有效中和肝素。
