The di-leucine motif contributes to class A scavenger receptor-mediated internalization of acetylated lipoproteins
The di-leucine motif contributes to class A scavenger receptor-mediated internalization of acetylated lipoproteins
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DOI：
10.1161/01.atv.0000220171.50282.0c
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发表时间：
2006-06-01
影响因子：
8.7
通讯作者：
Chen, Qi
中科院分区：
文献类型：
--
作者：
Chen, Yaoyu;Wang, Xiaohua;Chen, Qi
双亮氨酸基序存在于某些细胞表面受体的胞内结构域，参与受体介导的内吞作用。本研究的目的是确定的作用，在A类清道夫受体（SR-A）介导的配体endocytosis.Methods和Results-cDNA编码的突变体（SR-A突变体N3132 LM）与删除的双亮氨酸结构转染到中国仓鼠卵巢（CHO）细胞中的双亮氨酸基序。与野生型SR-A表达细胞相比，表达SR-A突变体N3132 LM的细胞显示出对SR-A配体乙酰化低密度脂蛋白（AcLDL）的摄取显著降低，但几乎没有变化。Western印迹分析显示SR-A突变体和网格蛋白从突变体而不是野生型CHO细胞的裂解物中共免疫沉淀，表明AcLDL结合的SR-A突变体N3132 LM与细胞膜的网格蛋白包被的小凹相关。从SR-A N-末端去除前27个氨基酸残基进一步降低了AcLDL摄取的细胞与di-leucine motif mutation.Conclusions-The di-leucine motif的SR-A胞内域有助于SR-A介导的细胞内化的AcLDL。双亮氨酸对存在于A类清道夫受体的胞质结构域。表达双亮氨酸突变体的细胞表现出降低的摄取和不变的结合AcLDL。双亮氨酸对不相关的涂层坑。这表明双亮氨酸基序是介导SR-A进入细胞的信号序列。
Objective-The di-leucine motif exists in the intracellular domains of certain cell surface receptors, participating in the receptor-mediated endocytosis. The present study was aimed at determining the role of the di-leucine motif in class A scavenger receptor (SR-A)-mediated ligand endocytosis.Methods and Results-cDNA coding for a mutant (SR-A mutant N3132LM) with deletion of the di-leucine structure was transfected into Chinese hamster ovary (CHO) cells. Compared with wild-type SR-A-expressing cells, the cells expressing the SR-A mutant N3132LM showed a significant decrease in uptake but almost no change in binding of the SR-A ligand acetylated low-density lipoprotein (AcLDL). Western blot analysis revealed coimmunoprecipitation of SR-A mutant and clathrin from the lysates of the mutant but not wild-type CHO cells, suggesting that AcLDL-bound SR-A mutant N3132LM is associated with the clathrin-coated pit of cellular membrane. Removal of the first 27 amino acid residues from the SR-A N-terminus further reduced AcLDL uptake by the cells with the di-leucine motif mutation.Conclusions-The di-leucine motif of SR-A intracellular domain contributes to the SR-A -mediated cellular internalization of AcLDL. Di-leucine pair exists in the cytoplasmic domain of class A scavenger receptor. The cells expressing di-leucine mutants showed decreased uptake and unchanged binding of AcLDL. The di-leucine pair was not associated to coated pits. It suggests that di-leucine motif acts as a signal sequence to mediate SR-A into cell.