Scavenging of 14-3-3 proteins reveals their involvement in the cell-surface transport of ATP-sensitive K+ channels
Scavenging of 14-3-3 proteins reveals their involvement in the cell-surface transport of ATP-sensitive K+ channels
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DOI：
10.1242/jcs.03196
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发表时间：
2006-10-15
影响因子：
4
通讯作者：
Schwappach, Blanche
中科院分区：
文献类型：
--
作者：
Heusser, Katja;Yuan, Hebao;Schwappach, Blanche
基于精氨酸(Arg)的内质网(ER)定位信号参与了不同异多聚体膜蛋白复合体的质量控制。ATP敏感性钾(K-ATP)通道是独一无二的，因为异八聚体中的每个亚基都包含一个基于Arg的内质网定位信号。我们已经剖析了覆盖八个肽排序基序的ER本地化活性的失活事件。利用14-3-3-清道夫结构来降低14-3-3蛋白的可获得性，我们发现14-3-3蛋白促进了异源表达和天然K-ATP通道的细胞表面表达。在一个胰岛β细胞系中检测到与K-ATP通道物理相关的14-3-3蛋白。我们的结果表明，Kir6.2中存在的基于Arg的信号被SUR1亚基立体掩蔽。相反，14-3-3蛋白在功能上拮抗SUR1中存在的基于Arg的信号。最后10个氨基酸是有效地募集到Kir6.2C末端多聚体所需的14-3-3。含有缺乏这些残基的造孔亚基的通道到达细胞表面的效率很低，但在功能上与全长亚基形成的通道无法区分。综上所述，14-3-3蛋白促进正确组装的复合体的细胞表面转运，但不调节细胞表面K-ATP通道的活性。
Arginine (Arg)-based endoplasmic reticulum (ER)-localization signals are involved in the quality control of different heteromultimeric membrane protein complexes. ATP-sensitive potassium (K-ATP) channels are unique because each subunit in the heterooctamer contains an Arg- based ER-localization signal. We have dissected the inactivation events that override the ER-localization activity of the eight peptide-sorting motifs. Employing a 14-3-3-scavenger construct to lower the availability of 14-3-3 proteins, we found that 14-3-3 proteins promote the cell-surface expression of heterologously expressed and native K-ATP channels. 14- 3- 3 proteins were detected in physical association with K-ATP channels in a pancreatic beta-cell line. Our results suggest that the Arg-based signal present in Kir6.2 is sterically masked by the SUR1 subunit. By contrast, 14-3-3 proteins functionally antagonized the Arg-based signal present in SUR1. The last ten amino acids were required for efficient 14-3-3 recruitment to multimeric forms of the Kir6.2 C-terminus. Channels containing a pore-forming subunit lacking these residues reached the cell surface inefficiently but were functionally indistinguishable from channels formed by the full-length subunits. In conclusion, 14-3-3 proteins promote the cell-surface transport of correctly assembled complexes but do not regulate the activity of K-ATP channels at the cell surface.