EVIDENCE FOR A 2-STEP MECHANISM INVOLVED IN ASSEMBLY OF FUNCTIONAL SIGNAL RECOGNITION PARTICLE RECEPTOR
EVIDENCE FOR A 2-STEP MECHANISM INVOLVED IN ASSEMBLY OF FUNCTIONAL SIGNAL RECOGNITION PARTICLE RECEPTOR
复制标题
DOI：
10.1083/jcb.108.3.797
复制
发表时间：
1989-03-01
影响因子：
7.8
通讯作者：
LINGAPPA, VR
中科院分区：
文献类型：
--
作者：
ANDREWS, DW;LAUFFER, L;LINGAPPA, VR
信号识别颗粒（SRP）和SRP受体依次作用，将新生分泌蛋白靶向ER膜。SRP受体由两个亚基组成，SR α。和SR β，两者都与内质网膜紧密相连。为了检测SRP受体的生物发生，我们开发了一种无细胞测定系统，其重建SR α。膜组件，并允许锚定和功能性质被独立地测定。我们的实验揭示了一种机制，涉及至少两个不同的步骤，靶向ER和锚定的靶分子的细胞质表面的膜。这两个步骤可以在体外重建，以恢复易位活性的ER微粒体与N-乙基-马来酰亚胺烷基化失活。该途径阐明的特征将其与分泌蛋白的SRP依赖性靶向、蛋白质如前孕激素的SRP非依赖性ER易位以及细胞色素b5例示的直接插入机制区分开来。
The signal recognition particle (SRP) and SRP receptor act sequentially to target nascent secretory proteins to the membrane of the ER. The SRP receptor consists of two subunits, SR.alpha. and SR.beta., both tightly associated with the ER membrane. To examine the biogenesis of the SRP receptor we have developed a cell-free assay system that reconstitutes SR.alpha. membrane assembly and permits and both anchoring and fucntional properties to be assayed independently. Our experiments reveal a mechanism involving at least two distinct steps, targeting to the ER and anchoring of the targeted molecule on the cytoplasmic face of the membrane. Both steps can be reconstituted in vitro to restore translocation activity to ER microsomes inactivated by alkylation with N-ethyl-maleimide. The characteristics elucidated for this pathway distinguish it from SRP-dependent targeting of secretory proteins, SRP-independent ER translocation of proteins such as prepromellitin, and direct insertion mechanisms of the type exemplifed by cytochrome b5.