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Unformatted text preview: Translation: Translation start site 5’-mRNA---AGGAGG----AUG---3’ Shine-Dalgarno + 30s 50s Of 30s bps to SD seq 1. Initiation of translation: a. Prokaryotic: 1) IF3 helps beind 30s with Shine-Dalgarno sequence (AGGAGG) 2) IF2+GTP helps bind tRNA (N-formyl) and helps 30s subunit scan along strand 3) IF1+n-formyl-methionyl tRNA binds to mRNA at proper AUG start codon (establishes ORF) 4) 50s subunit binds to mRNA this forms complete 70s ribosome 5) Deformylase removes n-formyl later on b. Eukaryotic: 1) eIF1a binds to ribosome: like IF1 FXNS to prevent large subunit from binding b4 start codon 2) eIF3 binds like IF3 3) eIF2+GTP: like IF2 helps bind 1 st tRNA molecule (met-tRNA) at proper start site 4) eIF4: a. 4a: binds mRNA upstream b. 4e: binds to 5’ cap c. 4g: binds to poly A tail 5) eIF4B: activates helicase activity of eIF4A 6) eIF5b+GTP: help recruit 60s subunit at this point the ribosome is 80s 40s 43s 48s 80s 2. elongation a. prokaryotic 1) EF-TU +GTP+tRNA--AA...
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