Protein SRP68 of human signal recognition particle: Identification of the RNA and SRP72 binding domains
Protein SRP68 of human signal recognition particle: Identification of the RNA and SRP72 binding domains
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DOI：
10.1110/ps.051861406
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发表时间：
2006-06-01
期刊：
影响因子：
8
通讯作者：
Zwieb, Christian
中科院分区：
文献类型：
--
作者：
Iakhiaeva, Elena;Bhuiyan, Shakhawat Hossain;Zwieb, Christian
信号识别颗粒(SRP)在将分泌蛋白输送到细胞膜中起着重要作用。哺乳动物的SRP由六个多肽组成，其中SRP68和SRP72形成了一个异源二聚体，这是出了名的难以研究。从高效表达的大肠杆菌中纯化了人SRP68，并发现其与重组SRP72和体外转录的人SRP RNA结合。基本上覆盖整个SRP68分子的多肽片段是通过重组或通过蛋白水解酶产生的。SRP68的RNA结合区包括52-252位残基。SRP68 C末端附近的94个氨基酸参与了与SRP72的结合。SRP68-SRP72的相互作用在盐浓度升高时保持稳定，并与SRP72 N末端的150个氨基酸结合。SRP72的这一部分位于一个预测的串联阵列中，该阵列由四个四肽(TPR)样基序组成，建议形成一个具有凹槽的超螺旋结构，以适应SRP68的C-末端区域。
The signal recognition particle (SRP) plays an important role in the delivery of secretory proteins to cellular membranes. Mammalian SRP is composed of six polypeptides among which SRP68 and SRP72 form a heterodimer that has been notoriously difficult to investigate. Human SRP68 was purified from overexpressing Escherichia coli cells and was found to bind to recombinant SRP72 as well as in vitro-transcribed human SRP RNA. Polypeptide fragments covering essentially the entire SRP68 molecule were generated recombinantly or by proteolytic digestion. The RNA binding domain of SRP68 included residues from positions 52 to 252. Ninety-four amino acids near the C terminus of SRP68 mediated the binding to SRP72. The SRP68-SRP72 interaction remained stable at elevated salt concentrations and engaged similar to 150 amino acids from the N-terminal region of SRP72. This portion of SRP72 was located within a predicted tandem array of four tetratricopeptide (TPR)-like motifs suggested to form a superhelical structure with a groove to accommodate the C-terminal region of SRP68.