MBIO 2020 Lecture Notes - Lecture 7: Aminoacyl Trna Synthetase, Start Codon, Transfer Rna
25 Nov 2017
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Initiation of translation: assembled ribosome has 3 sites, 1. E (exit: rbs positions ribosome at the initiation or start codon (aug) Initiator trna is n-formylmethionine p site first. If-3- prevents 30s subunit from binding the 50s subunit prematurely. If-1 will bind to mrna: 2. fmet~trna fmet binds to aug in the p site and if-2. If-2 binds gtp and directs attachment of fmet~trnafmet to the 30s subunit: amino acylated trna abinds both if2 and aug codon, anticodon of fmet-trnafmet is complementary to the start codon of mrna. If-1 binds 30s subunit removing if-3 and forming the 30s initiation complex: 3. Formation of the 70s initiation complex: 50s subunit binds to 30s, the result is an intact ribosome holds the mrna and fmet~trnafmet in. If-2 hydrolyzes gtp to gdp + pi helping 50s subunit bind to 30s. If-1 helps remove if-2 and gdp from the ribosome the p site, making the 70s ribosome initiation complex: process diagrams:
