Chen Y.-LJIN-DER WEN2022-11-182022-11-18202210916490https://www.scopus.com/inward/record.uri?eid=2-s2.0-85130495447&doi=10.1073%2fpnas.2118099119&partnerID=40&md5=58d99571d695c14f3f2dda0fb08ae378https://scholars.lib.ntu.edu.tw/handle/123456789/625698SignificanceRibosomes translate the genetic codes of messenger RNA (mRNA) to make proteins. Translation must begin at the correct initiation site; otherwise, abnormal proteins will be produced. Here, we show that a short ribosome-specific sequence in the upstream followed by an unstructured downstream sequence is a favorable initiation site. Those mRNAs lacking either of these two characteristics do not associate tightly with the ribosome. Initiator transfer RNA (tRNA) and initiation factors facilitate the binding. However, when the downstream site forms structures, initiation factor 3 triggers the dissociation of the accommodated initiator tRNA and the subsequent disassembly of the ribosome-mRNA complex. Thus, initiation factors help the ribosome distinguish unfavorable structured sequences that may not act as the mRNA translation initiation site.initiation factors; optical tweezers; single-molecule; smFRET; translation initiationinitiation factor; messenger RNA; methionine transfer RNA; genetics; metabolism; protein synthesis; ribosome; translation initiation; Peptide Chain Initiation, Translational; Peptide Initiation Factors; Protein Biosynthesis; Ribosomes; RNA, Messenger; RNA, Transfer, Metjournal article10.1073/pnas.2118099119356051252-s2.0-85130495447