Institute for Medical Sciences, School of Medicine, Ajou University, Suwon, South Korea.
Gene. 2010 Oct 15;466(1-2):16-25. doi: 10.1016/j.gene.2010.06.007. Epub 2010 Jun 23.
The human genome contains genes encoding for over 40 different types of kinesin and kinesin-like proteins. Of these, the functions of 13 kinesins remain uncharacterized. In this study, we constructed a plasmid containing the ORF of KIF18B and revealed that the KIF18B message of approximately 3kb is expressed in a tissue- and cell type-specific manners. A polypeptide of 842 amino acids was deduced from the ORF sequence. We identified another form of 873 amino acids which arises from alternative splicing at the C-terminal end. We also generated an anti-KIF18B antibody which detects a protein band of 120kDa. Western analyses showed that the protein level of KIF18B is elevated at late G(2) through metaphase, very similar to cyclin B1. Immunocytochemical staining revealed that the KIF18B protein is present predominantly in the nucleus and to a lesser extent in the cytoplasm of interphase cells. During mitosis, most KIF18B was found to be closely associated with astral microtubules emanating from the spindle pole during prometaphase and metaphase. Meanwhile, KIF18B was not detected at anaphase and telophase, consistent with the Western blotting data. The nuclear localization signal was roughly determined by using several EGFP-tagged deletion mutants of KIF18B. Together, the expression of KIF18B is regulated in a cell cycle-dependent manner and therefore may play an important role(s) in cell division.
人类基因组包含编码超过 40 种不同类型的驱动蛋白和驱动蛋白样蛋白的基因。其中，13 种驱动蛋白的功能尚未确定。在这项研究中，我们构建了一个包含 KIF18B ORF 的质粒，并揭示了大约 3kb 的 KIF18B 信使在组织和细胞类型特异性的方式下表达。从 ORF 序列推断出一个 842 个氨基酸的多肽。我们鉴定了另一种 873 个氨基酸的形式，它是在 C 末端的选择性剪接产生的。我们还生成了一种抗 KIF18B 抗体，它可以检测到 120kDa 的蛋白带。Western 分析显示，KIF18B 的蛋白水平在晚期 G2 期到中期升高，与细胞周期蛋白 B1 非常相似。免疫细胞化学染色显示，KIF18B 蛋白主要存在于间期细胞的核内，在细胞质中也有少量存在。在有丝分裂过程中，大多数 KIF18B 被发现与从前期到中期纺锤体极发出的星体微管密切相关。同时，在后期和末期没有检测到 KIF18B，与 Western blotting 数据一致。通过使用几种 EGFP 标记的 KIF18B 缺失突变体，大致确定了核定位信号。总之，KIF18B 的表达是细胞周期依赖性的，因此可能在细胞分裂中发挥重要作用。
