GAKIN, a novel kinesin-like protein associates with the human homologue of the Drosophila discs large tumor suppressor in T lymphocytes
GAKIN, a novel kinesin-like protein associates with the human homologue of the Drosophila discs large tumor suppressor in T lymphocytes
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DOI：
10.1074/jbc.m000715200
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发表时间：
2000-09-15
影响因子：
4.8
通讯作者：
Chishti, AH
中科院分区：
文献类型：
--
作者：
Hanada, T;Lin, LH;Chishti, AH
皮质细胞骨架的重组是T淋巴细胞活化的标志。在与抗原呈递细胞结合后，T细胞迅速经历细胞骨架重组，从而在细胞-细胞接触位点形成帽，导致受体聚集、蛋白质分离和细胞极化。在此之前，我们报道了果蝇盘大肿瘤抑制蛋白（hDlg）的人类淋巴细胞同源物的克隆，在这里，我们表明，一种新的蛋白质称为GAKIN结合到鸟苷酸激酶样结构域的hDlg，亲和蛋白纯化，肽测序，和克隆的GAKIN cDNA从Jurkat J77淋巴细胞确定GAKIN作为一个新的成员的驱动蛋白超家族的马达蛋白。GAKIN mRNA广泛表达，预测的氨基酸序列与果蝇驱动蛋白-73马达蛋白具有显著的序列相似性。GAKIN序列在NH末端含有一个马达结构域，一个中央茎结构域，和一个在COOH末端的被称为CAP-Gly结构域的推定微管相互作用序列。在所研究的MAGUK超家族蛋白中，GAKIN结合PSD-95的鸟苷酸激酶样结构域，但不结合p55的鸟苷酸激酶样结构域。hDlg和GAKIN主要定位于静息T淋巴细胞的细胞质中，然而，在CD 2受体交联后，hDlg可以易位至淋巴细胞帽。我们认为GAKIN-hDlg相互作用为MAGUKs与微管细胞骨架偶联的一般模式奠定了基础，并且这种相互作用对于MAGUKs和相关蛋白复合物在体内的细胞内运输可能具有重要的功能。
Reorganization of the cortical cytoskeleton is a hallmark of T lymphocyte activation, Upon binding to antigen presenting cells, the T cells rapidly undergo cytoskeletal re-organization thus forming a cap at the cell-cell contact site leading to receptor clustering, protein segregation, and cellular polarization. Previously, we reported cloning of the human lymphocyte homologue of the Drosophila Discs Large tumor suppressor protein (hDlg), Here we show that a novel protein termed GAKIN binds to the guanylate kinase-like domain of hDlg, Affinity protein purification, peptide sequencing, and cloning of GAKIN cDNA from Jurkat J77 lymphocytes identified GAKIN as a novel member of the kinesin superfamily of motor proteins. GAKIN mRNA is ubiquitously expressed, and the predicted amino acid sequence shares significant sequence similarity with the Drosophila kinesin-73 motor protein. GAKIN sequence contains a motor domain at the NH, terminus, a central stalk domain, and a putative microtubule-interacting sequence called the CAP-Gly domain at the COOH terminus, Among the MAGUK superfamily of proteins examined, GAKIN binds to the guanylate kinase-like domain of PSD-95 but not of p55. The hDlg and GAKIN are localized mainly in the cytoplasm of resting T lymphocytes, however, upon CD2 receptor cross-linking the hDlg can translocate to the lymphocyte cap. We propose that the GAKIN-hDlg interaction lays the foundation for a general paradigm of coupling MAGUKs to the microtubule-based cytoskeleton, and that this interaction may be functionally important for the intracellular trafficking of MAGUKs and associated protein complexes in vivo.