CHARACTERIZATION OF DLC-A AND DLC-B, 2 FAMILIES OF CYTOPLASMIC DYNEIN LIGHT-CHAIN SUBUNITS
CHARACTERIZATION OF DLC-A AND DLC-B, 2 FAMILIES OF CYTOPLASMIC DYNEIN LIGHT-CHAIN SUBUNITS
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DOI：
10.1091/mbc.5.6.645
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发表时间：
1994-06-01
影响因子：
3.3
通讯作者：
SCHROER, TA
中科院分区：
文献类型：
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作者：
GILL, SR;CLEVELAND, DW;SCHROER, TA
细胞质动力蛋白是一种负末端定向的微管依赖性马达，由两条重链（类似于530 kDa）、三条中间链（类似于74 kDa）和一个类似于52-61 kDa轻链的家族组成。虽然类似于530 kDa的亚基包含复合物的马达和微管结合结构域，但较小亚基的功能尚不清楚。使用二维凝胶电泳和蛋白水解图谱，我们发现轻链由两个主要家族组成，一个较高的M（r）家族（58，59，61 kDa;动力蛋白轻链A组[DLC-A]）和较低的M（r）家族（52，53，55，56 kDa;动力蛋白轻链B组[DLC-B]）。细胞质动力蛋白复合物与碘化钾的解离揭示了所有轻链多肽与类似于530 kDa的重链紧密相关，而类似于74 kDa的中间链多肽更容易提取。用碱性磷酸酶处理改变了四种轻链多肽的迁移率，表明这些亚基被磷酸化。编码DLC-A家族一个成员的cDNA克隆的测序揭示了预测的球状结构，其与任何已知蛋白质都不同源，但确实含有许多潜在的磷酸化位点和一致的核苷酸结合基序。
Cytoplasmic dynein is a minus-end-directed, microtubule-dependent motor composed of two heavy chains (similar to 530 kDa), three intermediate chains (similar to 74 kDa), and a family of similar to 52-61 kDa light chains. Although the similar to 530 kDa subunit contains the motor and microtubule binding domains of the complex, the functions of the smaller subunits are not known. Using two-dimensional gel electrophoresis and proteolytic mapping, we show here that the light chains are composed of two major families, a higher M(r) family (58, 59, 61 kDa; dynein light chain group A [DLC-A]) and lower M(r) family (52, 53, 55, 56 kDa; dynein light chain group B [DLC-B]). Dissociation of the cytoplasmic dynein complex with potassium iodide reveals that all light chain polypeptides are tightly associated with the similar to 530 kDa heavy chain, whereas the similar to 74 kDa intermediate chain polypeptides are more readily extracted. Treatment with alkaline phosphatase alters the mobility of four of the light chain polypeptides, indicating that these subunits are phosphorylated. Sequencing of a cDNA clone encoding one member of the DLC-A family reveals a predicted globular structure that is not homologous to any known protein but does contain numerous potential phosphorylation sites and a consensus nucleotide-binding motif.