Cadherin interaction probed by atomic force microscopy
Cadherin interaction probed by atomic force microscopy
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DOI：
10.1073/pnas.070052697
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发表时间：
2000-04-11
影响因子：
11.1
通讯作者：
Drenckhahn, D
中科院分区：
文献类型：
--
作者：
Baumgartner, W;Hinterdorfer, P;Drenckhahn, D
用单分子原子力显微镜对复合材料的结构、结合强度、结合强度等进行了表征（解结合力）和经典钙粘蛋白，血管内皮（VE）-钙粘蛋白的结合动力学，所述钙粘蛋白由转染的中国仓鼠卵巢细胞分泌为与人IgC的Fc部分融合的顺式二聚化全长外部结构域。VE-钙粘蛋白二聚体的外部结构域是大约20-nm长的杆状分子，（V形结构）在没有Ca 2+的情况下，二聚体的反式相互作用是低亲和力反应（K-D = 10（-3-）10（-5）M，k（off）= 1.8 s（-1），k（on）= 10（3）-10（5）M-1 s（-1）），具有相对低的解束缚力（在200- 4，000 nm.s（-1）的回扫速度下为35-55 pN），随着相互作用时间增加的高阶解束缚力，表明钙粘蛋白结合成具有累积结合强度复合物。这些观察结果有利于一个模型，固有的弱单位结合强度和亲和力的钙粘蛋白反式相互作用需要集群和细胞骨架固定扩增。结合受低亲和力Ca ~（2+）结合位点（KD = 1.15 mM）和高协同性（Hill系数为5.04）的调节。在狭窄的细胞间隙中，细胞外游离Ca ~（2+）的局部变化可能对促进细胞间粘附和通讯的快速重塑具有重要的生理意义。
Single molecule atomic force microscopy was used to characterize structure, binding strength (unbinding force), and binding kinetics of a classical cadherin, vascular endothelial (VE)-cadherin, secreted by transfected Chinese hamster ovary cells as cis-dimerized full-length external domain fused to Fc-portion of human IgC, In physiological buffer, the external domain of VE-cadherin dimers is a approximate to 20-nm-long rod-shaped molecule that collapses and dissociates into monomers (V-shaped structures) in the absence of Ca2+ Trans-interaction of dimers is a low-affinity reaction (K-D = 10(-3-)10(-5) M, k(off) = 1.8 s(-1), k(on) = 10(3)-10(5) M-1 s(-1)) with relatively low unbinding force (35-55 pN at retrace velocities of 200-4,000 nm.s(-1)), Higher order unbinding forces, that increase with interaction time, indicate association of cadherins into complexes with cumulative binding strength. These observations favor a model by which the inherently weak unit binding strength and affinity of cadherin trans-interaction requires clustering and cytoskeletal immobilization for amplification. Binding is regulated by low-affinity Ca2+ binding sites (KD = 1.15 mM) with high cooperativity (Hill coefficient of 5.04), Local changes of free extracellular Ca2+ in the narrow intercellular space may be of physiological importance to facilitate rapid remodeling of intercellular adhesion and communication.