Yang Z, Goldstein L S
Howard Hughes Medical Institute, Division of Cellular and Molecular Medicine, Department of Pharmacology, University of California San Diego, La Jolla, CA 92093-0683, USA.
Mol Biol Cell. 1998 Feb;9(2):249-61. doi: 10.1091/mbc.9.2.249.
Proteins of the kinesin superfamily define a class of microtubule-dependent motors that play crucial roles in cell division and intracellular transport. To study the molecular mechanism of axonal transport, a cDNA encoding a new kinesin-like protein called KIF3C was cloned from a mouse brain cDNA library. Sequence and secondary structure analysis revealed that KIF3C is a member of the KIF3 family. In contrast to KIF3A and KIF3B, Northern and Western analysis indicated that KIF3C expression is highly enriched in neural tissues such as brain, spinal cord, and retina. When anti-KIF3C antibodies were used to stain the cerebellum, the strongest signal came from the cell bodies and dendrites of Purkinje cells. In retina, anti-KIF3C mainly stains the ganglion cells. Immunolocalization showed that the KIF3C motor in spinal cord and sciatic nerve is mainly localized in cytoplasm. In spinal cord, the KIF3C staining was punctate; double labeling with anti-giantin and anti-KIF3C showed a clear concentration of the motor protein in the Golgi complex. Staining of ligated sciatic nerves demonstrated that the KIF3C motor accumulated at the proximal side of the ligated nerve, which suggests that KIF3C is an anterograde motor. Immunoprecipitation experiments revealed that KIF3C and KIF3A, but not KIF3B, were coprecipitated. These data, combined with previous data from other labs, indicate that KIF3C and KIF3B are "variable" subunits that associate with a common KIF3A subunit, but not with each other. Together these results suggest that KIF3 family members combinatorially associate to power anterograde axonal transport.
驱动蛋白超家族的蛋白质定义了一类依赖微管的马达蛋白，它们在细胞分裂和细胞内运输中发挥着关键作用。为了研究轴突运输的分子机制，从鼠脑cDNA文库中克隆了一个编码名为KIF3C的新型驱动蛋白样蛋白的cDNA。序列和二级结构分析表明，KIF3C是KIF3家族的成员。与KIF3A和KIF3B不同，Northern和Western分析表明，KIF3C的表达在脑、脊髓和视网膜等神经组织中高度富集。当使用抗KIF3C抗体对小脑进行染色时，最强的信号来自浦肯野细胞的细胞体和树突。在视网膜中，抗KIF3C主要染色神经节细胞。免疫定位显示，脊髓和坐骨神经中的KIF3C马达蛋白主要定位于细胞质中。在脊髓中，KIF3C染色呈点状；用抗巨蛋白和抗KIF3C进行双重标记显示，马达蛋白在高尔基体复合体中明显聚集。对结扎的坐骨神经进行染色表明，KIF3C马达蛋白在结扎神经的近端积累，这表明KIF3C是一种顺行马达蛋白。免疫沉淀实验表明，KIF3C和KIF3A（而非KIF3B）能共沉淀。这些数据与其他实验室先前的数据相结合，表明KIF3C和KIF3B是与共同的KIF3A亚基相关联的“可变”亚基，但它们彼此之间不相关联。这些结果共同表明，KIF3家族成员通过组合方式相互关联，为轴突顺行运输提供动力。
