Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA.
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA.
J Cell Biol. 2021 Nov 1;220(11). doi: 10.1083/jcb.202103079. Epub 2021 Oct 6.
The guided entry of tail-anchored protein (GET) pathway, in which the Get3 ATPase delivers an essential class of tail-anchored membrane proteins (TAs) to the Get1/2 receptor at the endoplasmic reticulum, provides a conserved mechanism for TA biogenesis in eukaryotic cells. The membrane-associated events of this pathway remain poorly understood. Here we show that complex assembly between the cytosolic domains (CDs) of Get1 and Get2 strongly enhances the affinity of the individual subunits for Get3•TA, thus enabling efficient capture of the targeting complex. In addition to the known role of Get1CD in remodeling Get3 conformation, two molecular recognition features (MoRFs) in Get2CD induce Get3 opening, and both subunits are required for optimal TA release from Get3. Mutation of the MoRFs attenuates TA insertion into the ER in vivo. Our results demonstrate extensive cooperation between the Get1/2 receptor subunits in the capture and remodeling of the targeting complex, and emphasize the role of MoRFs in receptor function during membrane protein biogenesis.
尾部锚定蛋白（TA）的定向进入（GET）途径，其中 Get3 ATP 酶将一类必需的尾部锚定膜蛋白（TA）递送到内质网处的 Get1/2 受体，为真核细胞 TA 生物发生提供了一种保守的机制。该途径的膜相关事件仍知之甚少。在这里，我们表明 Get1 和 Get2 的细胞质结构域（CD）之间的复合物组装强烈增强了各个亚基与 Get3•TA 的亲和力，从而能够有效地捕获靶向复合物。除了已知的 Get1CD 在重塑 Get3 构象中的作用外，Get2CD 中的两个分子识别特征（MoRF）诱导 Get3 打开，并且两个亚基对于从 Get3 中最佳释放 TA 都是必需的。MoRF 的突变会减弱 TA 在体内插入内质网。我们的结果表明，Get1/2 受体亚基在捕获和靶向复合物的重塑过程中进行了广泛的合作，并强调了 MoRF 在膜蛋白生物发生过程中受体功能中的作用。
