Inositol polyphosphate receptor and clathrin assembly protein AP-2 are related proteins that form potassium-selective ion channels in planar lipid bilayers.
Inositol polyphosphate receptor and clathrin assembly protein AP-2 are related proteins that form potassium-selective ion channels in planar lipid bilayers.
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肌醇多磷酸受体和网格蛋白组装蛋白 AP-2 是在平面脂质双层中形成钾选择性离子通道的相关蛋白。
DOI：
10.1073/pnas.89.19.8976
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发表时间：
1992
影响因子：
11.1
通讯作者：
Fleischer,S
中科院分区：
文献类型：
--
作者：
Timerman,AP;Mayrleitner,MM;Lukas,TJ;Chadwick,CC;Saito,A;Watterson,DM;Schindler,H;Fleischer,S
我们以前已经描述了肌醇多磷酸受体（IPxRec），从洗涤剂溶解的牛小脑微粒体中纯化，在平面脂质双层中显示钾离子通道活性。我们现在发现IPxRec与网格蛋白组装蛋白AP-2密切相关。从牛脑网格蛋白包被的囊泡中纯化的IPxRec和AP-2具有几个结构和功能特征：（i）相似的亚基组成;各自具有四个具有相似迁移率的主要多肽（Mr值为111，000、100，000、50，000和17，000）和相对强度，通过SDS/PAGE分析;（ii）通过分子筛色谱法研究的类似尺寸（iii）Mr 50，000亚基和Mr 111，000/100，000双联体的相同N-末端氨基酸序列;（iv）AP-2 Mr 111，000/100，000双联体与针对IPxRec的双联体蛋白质亲和纯化的多克隆抗体的免疫反应性;（v）展示装配蛋白质的体外诊断特征-即，它们诱导网格蛋白笼的组装;和（vi）当掺入平面脂质双层时，对具有相同单位电导的钾离子具有选择性的离子通道活性。发现一个差异：AP-2通道不像报道的IPx受体通道那样被肌醇1，3，4，5-四磷酸阻断。这些研究表明IPx信号通路和受体介导的内吞作用之间可能存在联系。
We have previously described an inositol polyphosphate receptor (IPxRec), purified from detergent-solubilized bovine cerebellum microsomes, that displays potassium ion channel activity in planar lipid bilayers. We now find that the IPxRec is closely related to clathrin assembly protein AP-2. The IPxRec and AP-2 purified from bovine brain clathrin-coated vesicles share several structural and functional features: (i) similar subunit composition; each has four major polypeptides that have similar mobility (Mr values of 111,000, 100,000, 50,000, and 17,000) and relative intensity by SDS/PAGE analysis; (ii) similar size as studied by molecular sieve chromatography (Mr 400,000); (iii) identical N-terminal amino acid sequences for the Mr 50,000 subunits and Mr 111,000/100,000 doublets; (iv) immunoreactivity of the AP-2 Mr 111,000/100,000 doublet to polyclonal antibodies affinity purified against the doublet proteins of the IPxRec; (v) display of the in vitro diagnostic feature of assembly proteins--i.e., they induce the assembly of clathrin cages; and (vi) ion channel activity selective for potassium ions with the same unitary conductance when incorporated into planar lipid bilayers. One difference was found. AP-2 channels were not blocked by inositol 1,3,4,5-tetraphosphate as reported for IPx receptor channels. These studies suggest a possible connection between the IPx signaling pathways and receptor-mediated endocytosis.