Interactions of annexins with the mu subunits of the clathrin assembly proteins
Interactions of annexins with the mu subunits of the clathrin assembly proteins
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DOI：
10.1021/bi051160w
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发表时间：
2005-10-25
期刊：
影响因子：
2.9
通讯作者：
Snyder, SL
中科院分区：
文献类型：
--
作者：
Creutz, CE;Snyder, SL
许多生物化学和遗传学研究表明，某些膜联蛋白在内吞途径中发挥重要作用，可能涉及内吞区室的产生、定位或融合。在酵母双杂交筛选与膜联蛋白A2的N-末端结构域相互作用的蛋白质中，我们鉴定了网格蛋白组装蛋白复合物AP-2的mu 2亚基。这种相互作用依赖于膜联蛋白中Yxx Phi氨基酸序列基序（Y =酪氨酸，x =可变残基，Phi =大体积疏水残基）的两个拷贝，这也是跨膜受体胞质结构域上mu 2结合位点的特征。μ 2和全长膜联蛋白A2之间的相互作用在体外被证明是直接的，需要钙，并且在膜联蛋白A2能够将μ 2募集到固定化脂质的意义上是功能性的。对其他膜联蛋白和μ亚基的研究表明，膜联蛋白A2也结合AP-1复合物的μ I亚基，膜联蛋白A6结合μ 1和μ 2，膜联蛋白A1仅结合μ 1。我们提出，膜联蛋白可以“伪装”为跨膜受体时，他们被连接到膜在钙的存在下，因此，他们可能会发挥作用，启动钙调节包被的小坑形成在细胞表面或细胞内细胞器。
A number of biochemical and genetic studies have suggested that certain annexins play important roles in the endocytic pathway, possibly involving the generation, localization, or fusion of endocytic compartments. In a yeast two-hybrid screen for proteins that interact with the N-terminal domain of annexin A2 we identified the mu2 subunit of the clathrin assembly protein complex AP-2. The interaction depended upon two copies of a Yxx Phi amino acid sequence motif (Y = tyrosine, x = variable residue, Phi = bulky, hydrophobic residue) in the annexin that is also characteristic of the binding site for mu2 on the cytoplasmic domains of transmembrane receptors. The interaction between mu2 and full-length annexin A2 was demonstrated in vitro to be direct, to require calcium, and to be functional in the sense that annexin A2 was able to recruit the mu2 to immobilized lipids. Examination of other annexins and mu subunits demonstrated that annexin A2 also binds the mu I subunit of the AP-1 complex, that annexin A6 binds mu1 and mu2, and that annexin A1 binds only mu1. We propose that annexins can "masquerade" as transmembrane receptors when they are attached to membranes in the presence of calcium and that they might therefore function to initiate calcium-regulated coated pit formation at the cell surface or on intracellular organelles.