MRC Centre for Neurodegeneration Research, Institute of Psychiatry, King's College London, PO Box 37, De Crespigny Park, Denmark Hill, London SE5 8AF, UK.
J Cell Sci. 2011 Apr 1;124(Pt 7):1032-42. doi: 10.1242/jcs.075168. Epub 2011 Mar 8.
Kinesin light chain 1 (KLC1) binds to the intracellular cytoplasmic domain of the type-1 membrane-spanning protein calsyntenin-1 (also known as alcadein-α) to mediate transport of a subset of vesicles. Here, we identify serine 460 in KLC1 (KLC1ser460) as a phosphorylation site and show that mutation of KLC1ser460 influences the binding of KLC1 to calsyntenin-1. Mutation of KLC1ser460 to an alanine residue, to preclude phosphorylation, increased the binding of calsyntenin-1, whereas mutation to an aspartate residue, to mimic permanent phosphorylation, reduced the binding. Mutation of KLC1ser460 did not affect the interaction of KLC1 with four other known binding partners: huntingtin-associated protein 1 isoform A (HAP1A), collapsin response mediator protein-2 (CRMP2), c-Jun N-terminal kinase-interacting protein-1 (JIP1) and kinase-D-interacting substrate of 220 kDa (Kidins220). KLC1ser460 is a predicted mitogen-activated protein kinase (MAPK) target site, and we show that extracellular-signal-regulated kinase (ERK) phosphorylates this residue in vitro. We also demonstrate that inhibition of ERK promotes binding of calsyntenin-1 to KLC1. Finally, we show that expression of the KLC1ser460 mutant proteins influences calsyntenin-1 distribution and transport in cultured cells. Thus, phosphorylation of KLC1ser460 represents a mechanism for selectively regulating the binding and trafficking of calsyntenin-1.
驱动蛋白轻链 1（KLC1）与跨膜蛋白 1 型细胞内胞质域的 calsyntenin-1（也称为 alcadein-α）结合，介导一组囊泡的运输。在这里，我们确定 KLC1 中的丝氨酸 460（KLC1ser460）为磷酸化位点，并表明 KLC1ser460 的突变会影响 KLC1 与 calsyntenin-1 的结合。将 KLC1ser460 突变为丙氨酸残基，以阻止磷酸化，会增加 calsyntenin-1 的结合，而突变为天冬氨酸残基，模拟永久性磷酸化，则会减少结合。KLC1ser460 的突变不影响 KLC1 与其他四个已知结合伙伴的相互作用：亨廷顿相关蛋白 1 同种型 A（HAP1A）、 collapsin 反应介质蛋白-2（CRMP2）、c-Jun N-末端激酶相互作用蛋白-1（JIP1）和 220kDa 激酶-D 相互作用底物（Kidins220）。KLC1ser460 是一个预测的丝裂原活化蛋白激酶（MAPK）靶位，我们表明细胞外信号调节激酶（ERK）在体外磷酸化该残基。我们还证明 ERK 的抑制促进 calsyntenin-1 与 KLC1 的结合。最后，我们表明 KLC1ser460 突变蛋白的表达会影响培养细胞中 calsyntenin-1 的分布和运输。因此，KLC1ser460 的磷酸化代表了一种选择性调节 calsyntenin-1 结合和运输的机制。
