Light chain-dependent regulation of Kinesin's interaction with microtubules.
Light chain-dependent regulation of Kinesin's interaction with microtubules.
复制标题
DOI：
10.1083/jcb.143.4.1053
复制
发表时间：
1998-11-16
期刊：
影响因子：
--
通讯作者：
Rapoport TA
中科院分区：
文献类型：
--
作者：
Verhey KJ;Lizotte DL;Abramson T;Barenboim L;Schnapp BJ;Rapoport TA
我们已经调查了机制，防止传统的驱动蛋白结合微管（MT）时，不运输货物。驱动蛋白重链（HC）在COS细胞中单独表达或与驱动蛋白轻链（LC）一起表达。免疫荧光显微镜和MT共沉淀实验表明，HC与MT的结合受到LC共表达的抑制。链之间的关联涉及LC NH 2-末端结构域，包括七肽重复序列，并且需要HC的区域，其包括茎结构域的保守区域和尾结构域的NH 2末端。MT结合的抑制还需要HC的COOH末端64个氨基酸。HC的尾部和马达结构域之间的相互作用得到沉降实验的支持，该实验表明驱动蛋白处于折叠构象。pH从7.2变化到6.8释放了对驱动蛋白的抑制，而不改变其沉降行为。COS细胞中的内源性驱动蛋白也显示出对MT结合的pH敏感性抑制。两者合计，我们的研究结果提供的证据表明，LC的功能是通过诱导HC的尾部和马达结构域之间的相互作用来保持驱动蛋白处于不活跃的基态;货物运输的激活可能由释放MT结合的马达结构域的抑制的小的构象变化触发。
We have investigated the mechanism by which conventional kinesin is prevented from binding to microtubules (MTs) when not transporting cargo. Kinesin heavy chain (HC) was expressed in COS cells either alone or with kinesin light chain (LC). Immunofluorescence microscopy and MT cosedimentation experiments demonstrate that the binding of HC to MTs is inhibited by coexpression of LC. Association between the chains involves the LC NH2-terminal domain, including the heptad repeats, and requires a region of HC that includes the conserved region of the stalk domain and the NH2 terminus of the tail domain. Inhibition of MT binding requires in addition the COOH-terminal 64 amino acids of HC. Interaction between the tail and the motor domains of HC is supported by sedimentation experiments that indicate that kinesin is in a folded conformation. A pH shift from 7.2 to 6.8 releases inhibition of kinesin without changing its sedimentation behavior. Endogenous kinesin in COS cells also shows pH-sensitive inhibition of MT binding. Taken together, our results provide evidence that a function of LC is to keep kinesin in an inactive ground state by inducing an interaction between the tail and motor domains of HC; activation for cargo transport may be triggered by a small conformational change that releases the inhibition of the motor domain for MT binding.