Institut Curie, U1006 INSERM, 26 rue d'Ulm, 75005 Paris, France.
J Mol Biol. 2011 Sep 9;412(1):72-9. doi: 10.1016/j.jmb.2011.07.013. Epub 2011 Jul 23.
Gap junction channels are intercellular channels that form by docking the extracellular loops of connexin protein subunits. While the structure and function of gap junctions as intercellular channels have been characterized using different techniques, the physics of the inter-connexin interaction remain unknown. Moreover, as far as we know, the capacity of gap junction channels to work as adhesion complexes supporting pulling forces has not yet been quantitatively addressed. We report the first quantitative characterization of the kinetics and binding strength of the interaction of a short peptide mimicking extracellular loop 2 of Cx26 with membrane-reconstituted Cx26, combining the imaging and force spectroscopy capabilities of atomic force microscopy. The fast dissociation rate inferred a dynamic bond, while the slow association rate reflected the reduced flexibility and small size of extracellular loops. Our results propose the gap junction channel as an adhesion complex that associates slowly and dissociates fast at low force but is able to support important pulling forces in its native, hexameric form.
缝隙连接通道是通过对接连接蛋白亚基的细胞外环形成的细胞间通道。虽然使用不同的技术已经对缝隙连接作为细胞间通道的结构和功能进行了表征，但细胞间连接的物理性质仍然未知。此外，据我们所知，缝隙连接通道作为支持拉力的黏附复合物的能力尚未得到定量解决。我们报告了第一个定量表征短肽模拟细胞外环 2 与膜重组 Cx26 相互作用的动力学和结合强度的研究，该研究结合了原子力显微镜的成像和力谱学功能。快速解离速率推断出动态键，而缓慢的缔合速率反映了细胞外环的柔韧性降低和尺寸较小。我们的研究结果提出了缝隙连接通道作为一种黏附复合物，它在低力下缓慢结合，快速解离，但在其天然六聚体形式下能够支撑重要的拉力。
