SOCR 330 Lecture Notes - Stop Codon, Peptidyl Transferase, Recognition Sequence
Document Summary
30s subunit binds to shine-dalgarno sequence (aggagg) in mrna upstream of start codon. 16s rrna within 30s subunit has sequence ccucc at 3" end. Forms initiation complex with if ( initiation factor ) proteins and gtp. Formylmethionine (fmet) placed on start codon within initiation complex. Remaining if proteins released, gtp hydrolyzed fmet trna bound to mrna in p site, a site vacant for next charged trna. Usually positioned as first amino acid in polypeptide chain as translation starts in prokaryotes. Almost always subsequently removed from final protein product. Kozak recognition sequence surrounds aug initiation codon (accaugg) Small ribosome subunit binds to mrna at kozak sequence. Aug codon essential for formation of initiation complex but no formylmethionine. Special trna (trnai met) placed on initiation codon. Peptidyl transferase moves new peptide chain from trna in p site to trna in a site. Peptide bond forms as next amino acid added. Ribosome moves forward to a site now occupies next codon on mrna.
