The crystal structure of the signal recognition particle Alu RNA binding heterodimer, SRP9/14
The crystal structure of the signal recognition particle Alu RNA binding heterodimer, SRP9/14
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DOI：
10.1093/emboj/16.13.3757
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发表时间：
1997-07-01
期刊：
影响因子：
11.4
通讯作者：
Aberg, A
中科院分区：
文献类型：
--
作者：
Birse, DEA;Kapp, U;Aberg, A
哺乳动物信号识别颗粒（signalrecognitionparticle，SRP）是一种11 S的胞质核糖核蛋白，在蛋白质分选中起重要作用，它识别核糖体上新生多肽链的信号序列，并将核糖体上的核糖体上升链-SRP复合物靶向粗面内质网，SRP由6条多肽组成（SRP 9、SRP 14、SRP 19、SRP 54、SRP 68和SRP 72）和单个300个核苷酸的RNA分子，SRP 9和SRP 14蛋白形成异二聚体，其结合到SRP RNA的Alu结构域，该结构域负责翻译停滞。在2.5埃分辨率下测定的小鼠SRP 9/14异二聚体的结构，发现SRP 9和SRP 14在结构上同源，含有相同的α-β-β-α折叠，我们将其命名为Alu结合模块（Alu bm），小α/β RNA结合结构域家族的另一成员，异二聚体具有假2重对称性并且是鞍状的，包含强烈弯曲的六链两亲性β-片层，其中四个螺旋堆积在凸面上，并且暴露的凹面衬有带正电荷的残基。
The mammalian signal recognition particle (SRP) is an 11S cytoplasmic ribonucleoprotein that plays an essential role in protein sorting, SRP recognizes the signal sequence of the nascent polypeptide chain emerging from the ribosome, and targets the ribosomenascent chain-SRP complex to the rough endoplasmic reticulum, The SRP consists of six polypeptides (SRP9, SRP14, SRP19, SRP54, SRP68 and SRP72) and a single 300 nucleotide RNA molecule, SRP9 and SRP14 proteins form a heterodimer that binds to the Alu domain of SRP RNA which is responsible for translation arrest, We report the first crystal structure of a mammalian SRP protein, that of the mouse SRP9/14 heterodimer, determined at 2.5 Angstrom resolution, SRP9 and SRP14 are found to be structurally homologous, containing the same alpha-beta-beta-beta-alpha fold, This we designate the Alu binding module (Alu bm), an additional member of the family of small alpha/beta RNA binding domains, The heterodimer has pseudo 2-fold symmetry and is saddle like, comprising a strongly curved six-stranded amphipathic beta-sheet with the four helices packed on the convex side and the exposed concave surface being lined with positively charged residues.