Interaction of the cytoplasmic tail of CTLA-4 (CD152) with a clathrin-associated protein is negatively regulated by tyrosine phosphorylation
Interaction of the cytoplasmic tail of CTLA-4 (CD152) with a clathrin-associated protein is negatively regulated by tyrosine phosphorylation
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DOI：
10.1021/bi971762i
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发表时间：
1997-12-16
期刊：
影响因子：
2.9
通讯作者：
Kurtz, SE
中科院分区：
文献类型：
--
作者：
Bradshaw, JD;Lu, P;Kurtz, SE
CTLA-4（CD 152）是CD 80和CD 86的高亲和力受体，是T细胞活化的强有力调节剂。虽然CTLA-4在细胞表面起作用，但其主要定位于细胞内囊泡中并循环至细胞表面。CTLA-4胞质结构域包含指导其细胞内定位并调节其信号传导的序列。在这里，我们证明了参与受体运输和信号传导的效应分子与CTLA-4胞质结构域中不同但重叠的序列相互作用。使用酵母双杂交方法，我们证明了AP-2的mu 2亚基，在质膜相关的包被凹坑中发现的网格蛋白相关复合物，与CTLA-4的胞质尾，但不是CD 28的关联。AP-1的mu 1亚基，发现于高尔基体相关的包被小窝中，与CTLA-4和CD 28均不相关。mu 2和CTLA-4相互作用所需的序列定位于CTLA-4中的残基（161）TTGVY;该序列与先前鉴定的涉及CTLA-4信号传导的SH 2结合基序（YVKM）-Y-165在N末端，但与其重叠。当残基Y-165非磷酸化时，mu 2优先与CTLA-4相互作用，而当Y-165磷酸化时，PI 3激酶SH 2结构域优先相互作用。在共转染实验中，CTLA-4的胞质尾区中的两个酪氨酸残基（Y-165和Y-182）被T淋巴细胞相关酪氨酸激酶p561 ck磷酸化。因此，CTLA-4残基Y-165的磷酸化可以通过确定哪些效应分子结合其胞质尾区来间接调节CTLA-4的信号传导和运输。
CTLA-4 (CD152), high-avidity receptor for CD80 and CD86, is a powerful regulator of T cell activation. While CTLA-4 functions at the cell surface, it is primarily localized in intracellular vesicles and cycles to the cell surface. The CTLA-4 cytoplasmic domain contains sequences that direct its intracellular localization and regulate its signaling. Here we demonstrate that effector molecules involved in receptor trafficking and signaling interact with distinct, but overlapping, sequences in the CTLA-4 cytoplasmic domain. Using the yeast two-hybrid method, we demonstrate association of the mu 2 subunit of AP-2, the clathrin-associated complex found in plasma membrane-associated coated pits, with the cytoplasmic tail of CTLA-4, but not CD28. The mu 1 subunit of AP-1, found in Golgi-associated coated pits, associated with neither CTLA-4 nor CD28. Sequences required for interaction of mu 2 and CTLA-4 were localized to residues, (161)TTGVY in CTLA-4; this sequence is N-terminal to, but overlaps with, a previously identified SH2 binding motif, (YVKM)-Y-165, involved in CTLA-4 signaling. mu 2 interacted preferentially with CTLA-4 when residue Y-165 was nonphosphorylated, whereas a PI3 kinase SH2 domain interacted preferentially when Y-165 was phosphorylated. In co-transfection experiments, both tyrosine residues in the cytoplasmic tail of CTLA-4 (Y-165 and Y-182) were phosphorylated by the T lymphocyte-associated tyrosine kinase, p561ck. Thus, phosphorylation of CTLA-4 residue Y-165 may reciprocally regulate signaling and trafficking of CTLA-4 by determining which effector molecules bind to its cytoplasmic tail.