Study BMB 400 Chap 14 Initiation of Translation Flash Cards

 
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BMB 400 Chap 14 Initiation of Translation

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-eIF4F (at 5’ end of mRNA) associates with 3’ end of mRNA through poly-A binding protein
-when ribosome done, ideally positioned to restart translation on same mRNA
-recycling!
scanning in euks
-The small subunit moves 5’->3’ along the mRNA in an ATP-dependent process driven by eIF4F-associated RNA helicase
-finds AUG, some IFs released
-large subunit binds, all IFs released
eIF4B
-removes any secondary structure of mRNA by RNA helicase activity.
eIF4F
-recognizes 5’ cap structure of mRNA
-helps move small subunit along mRNA (w/ ATP) to find AUG
-associates with 3’ end of mRNA through poly-A binding protein
translation initiation in euks
>30 different polypeptides are involved in initiation of translation in eukaryotes
IF3
keep ribosomal subunits apart

(has to leave 1st so ribosome can work)
after all 3 IFs bound,
the small subunit is prepared to bind the mRNA and the initiator tRNA
IF2
with GTP, brings fMet-tRNA to the P site on the small subunit
IF1
prevents tRNAs from binding to the portion of the small subunit that will become A site
aminopeptidases
remove the amino terminal methionine as well as one or two additional amino acids in pros
Deformylase
-removes the formyl group from the amino terminus during or after the synthesis of the polypeptide chain
-many pro proteins don't even have Met on N terminus
initiator tRNA in pro
N-formyl methionine
SD equence base pairing
(RBS, SD sequence) in the 5’ untranslated region and the 3’ end of the 16S rRNA
initiation in pro mRNA
-small subunit (30S) associates in mRNA
-base pairing b/w RBS and 16S rRNA
-AUG ideally in P site
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