Lecture 14

Lecture 14 - LS3 MOLECULAR BIOLOGY LECTURE 13 Overview...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
LS3 MOLECULAR BIOLOGY LECTURE 13 Overview      TRANSLATION II:  Ribosomes and Protein Synthesis Dr. Randolph Wall Reading:  Watson et al.  423-453, 458-459
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
tRNA Binding Sites on Ribosomes A site:   (A for aminoacyl-tRNA) aminoacyl-tRNA will enter at this site P site:(P for peptidyl-tRNA) new peptide bonds are formed at this site with  aminoacyl-tRNA E site:(E for exit site) transiently occupied by the uncharged tRNA that is leaving  the ribosome “Kink” in mRNA promotes codon recognition by tRNAs 50S subunit 30S subunit
Background image of page 2
E P A mRNA  (with “kink”) tRNA Codon 1 Codon 2 Site of peptide synthesis Interaction Between  Bound tRNAs and  mRNAs 3’
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Initiation Elongation Termination Three Phases of Translation Initiation   Formation of initiation complex, setting the initiator AUG, ORF      (different mechanisms in prokaryotes vs. eukaryotes) Elongation Peptide bond formation Translocation Termination Release of  the completed polypeptide     Dissociation of ribosomal subunits
Background image of page 4
In addition to ribosomes, non-ribosomal protein factors required Prokaryotic translation factors: Initiation factors (IF-1, IF-2, IF-3) Elongation factors (EF-Tu, EF-Ts, EF-G) Termination factors (RF-1, RF-2, RF-3-GTP) GTP hydrolysis drives conformational changes  ATP provides energy for peptide bond formation (from tRNA charging)  rRNAs play major functional roles in protein synthesis, rProteins mainly structural -16S rRNA “decoding center” mediates interactions of mRNA        codons with tRNA  anticodons -23S rRNA catalyzes peptide bond formation in “peptidyl       tranferase center” Important Features of Protein Synthesis
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Eukaryotic monocistronic mRNA Prokaryotic polycistronic mRNA Prokaryotic mRNA Initiate at AUG Set by 16S rRNA-RBS Binding, Eukaryotic  mRNA Initiate at First AUG After 5’ CAP 
Background image of page 6
Proper base pairing of fMet-tRNA to  AUG in mRNA  causes conformational change in 30S subunit which leads to  release of IF3, so 50S subunit is able to re-associate with  30S  Binding of the 50S subunit causes GTP hydrolysis,  releases IF2 and IF1 -> Assembly of 70S ribosome with A-site open for next  aminoacyl tRNA/EF-Tu-GTP  Overview of Prokaryotic Translation Initiation fMet-tRNA entry into P-site forms 30S pre- initiation complex followed by mRNA base  pairing to 16S rRNA for in-phase initiation (or mRNA base pairing to 16S rRNA can occur  first followed by fMet-tRNA entry into P-site)
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Eukaryotic Translation Initiation Overview  Assembled pre-initiation complex with Met- tRNAi in 40S subunit  P-site binds 5’ CAP of mRNA with bound eIF4 complex
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 41

Lecture 14 - LS3 MOLECULAR BIOLOGY LECTURE 13 Overview...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online