Zhou Q, Nakada M T, Brooks P C, Swenson S D, Ritter M R, Argounova S, Arnold C, Markland F S
Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California, 90033, USA.
Biochem Biophys Res Commun. 2000 Jan 7;267(1):350-5. doi: 10.1006/bbrc.1999.1965.
Contortrostatin is a homodimeric disintegrin from snake venom. We have shown that contortrostatin binds to integrins alphaIIbbeta3, alpha5beta1, and alphavbeta3. We now use several criteria to demonstrate the binding of contortrostatin to alphavbeta5. First, incubation of T24 cells, which express alphavbeta3 and alphavbeta5, with antibody against alphavbeta3 failed to completely inhibit adhesion of cells to vitronectin. However, pretreatment of the cells with contortrostatin or the combination of antibodies against alphavbeta3 and alphavbeta5 completely blocked adhesion to vitronectin. By contrast, either anti-alphavbeta5 alone or contortrostatin blocked adhesion of an alphavbeta3-negative T24 subline. Second, contortrostatin as well as anti-alphavbeta5 inhibits invasion of OVCAR-5, which express only alphavbeta5. Third, contortrostatin binds to purified alphavbeta5 in a saturable manner. Finally, radioligand binding assays yielded a K(d) value of 24 nM for [(125)I]contortrostatin binding to alphavbeta5. This investigation identifies alphavbeta5 as a binding site for contortrostatin. Blockage of alphavbeta5 by contortrostatin inhibits alphavbeta5-mediated adhesion and invasion.
扭曲毒素是一种来自蛇毒的同型二聚体解整合素。我们已经证明扭曲毒素能与整合素αIIbβ3、α5β1和αvβ3结合。我们现在使用多种标准来证明扭曲毒素与αvβ5的结合。首先，用抗αvβ3抗体孵育表达αvβ3和αvβ5的T24细胞，未能完全抑制细胞与玻连蛋白的黏附。然而，用扭曲毒素或抗αvβ3和抗αvβ5抗体的组合对细胞进行预处理，可完全阻断与玻连蛋白的黏附。相比之下，单独使用抗αvβ5或扭曲毒素均可阻断αvβ3阴性的T24亚系的黏附。其次，扭曲毒素以及抗αvβ5可抑制仅表达αvβ5的OVCAR-5细胞的侵袭。第三，扭曲毒素以可饱和的方式与纯化的αvβ5结合。最后，放射性配体结合试验得出[(125)I]扭曲毒素与αvβ5结合的K(d)值为24 nM。这项研究确定αvβ5是扭曲毒素的一个结合位点。扭曲毒素对αvβ5的阻断可抑制αvβ5介导的黏附和侵袭。
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