Block K L, Vornlocher H P, Hershey J W
Department of Biological Chemistry, School of Medicine, University of California, Davis, California 95616, USA.
J Biol Chem. 1998 Nov 27;273(48):31901-8. doi: 10.1074/jbc.273.48.31901.
Eukaryotic translation initiation factor 3 (eIF3) is a large multisubunit complex that plays a central role in the initiation of translation. It binds to 40 S ribosomal subunits resulting in dissociation of 80 S ribosomes, stabilizes initiator methionyl-tRNA binding to 40 S subunits, and is required for mRNA binding. eIF3 has an aggregate molecular mass of approximately 600 kDa and comprises at least 10 subunits. The cDNAs encoding eight of the subunits have been cloned previously (p170, p116, p110, p66, p48, p47, p40, and p36). Here we report the cloning and characterization of human cDNAs encoding two more subunits of human eIF3, namely eIF3-p44 and eIF3-p35. These proteins are immunoprecipitated by affinity-purified anti-eIF3-p170 antibodies, indicating they are components of the eIF3 complex. Far Western analysis shows that eIF3-p44 interacts strongly and specifically with the eIF3-p170 subunit, and weakly with p116/p110, p66, p40, and itself. eIF3-p44 contains an RNA recognition motif near its C terminus. Northwestern blotting shows that eIF3-p44 binds 18 S rRNA and beta-globin mRNA. Possession of cloned cDNAs encoding all 10 subunits of eIF3 provides the tools necessary to elucidate the functions of the individual subunits and the structure of the eIF3 complex.
真核生物翻译起始因子3（eIF3）是一种大型多亚基复合物，在翻译起始过程中起核心作用。它与40S核糖体亚基结合，导致80S核糖体解离，稳定起始甲硫氨酰 - tRNA与40S亚基的结合，并且是mRNA结合所必需的。eIF3的总分子量约为600kDa，包含至少10个亚基。先前已克隆了编码其中8个亚基的cDNA（p170、p116、p110、p66、p48、p47、p40和p36）。在此，我们报告了编码人eIF3另外两个亚基即eIF3 - p44和eIF3 - p35的人cDNA的克隆和表征。这些蛋白质可被亲和纯化的抗eIF3 - p170抗体免疫沉淀，表明它们是eIF3复合物的组成部分。Far Western分析表明，eIF3 - p44与eIF3 - p170亚基强烈且特异性地相互作用，与p116 / p110、p66、p40以及其自身的相互作用较弱。eIF3 - p44在其C末端附近含有一个RNA识别基序。Northwestern印迹显示eIF3 - p44结合18S rRNA和β - 珠蛋白mRNA。拥有编码eIF3所有10个亚基的克隆cDNA为阐明各个亚基的功能以及eIF3复合物的结构提供了必要的工具。
