The joining of ribosomal subunits in eukaryotes requires eIF5B

摘要: Initiation of eukaryotic protein synthesis begins with the ribosome separated into its 40S and 60S subunits. The subunit first binds initiation factor (eIF) 3 an eIF2-GTP-initiator transfer RNA ternary complex. resulting complex requires eIF1, eIF1A, eIF4A, eIF4B eIF4F to bind a messenger scan codon. eIF5 stimulates hydrolysis eIF2-bound GTP eIF2 is released from 48S formed at codon before it joined by form active 80S ribosome. Here we show that induced in complexes necessary but not sufficient for subunits join. A second termed eIF5B (relative molecular mass 175,000) essential this process. It homologue prokaryotic IF2 (re and, like it, mediates joining has ribosome-dependent GTPase activity function.