期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 97, 期 8, 页码 4005-4010出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.070052697
关键词
cell adhesion; VE-cadherin; binding strength; binding kinetics
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.
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