Eukaryotic mRNA translation: Ribosome structure,
function, and translational control
Dr. Jeff Coller
RNA Center
Office: W113 (Wood Bldg.)
P 368-0299
C 543-3258
E jmc71@case.edu
Ribosome Biosynthesis
Chemical modification and nucleolytic processing of the Eukaryotic 45S rRNA precursor
Modifications of the precursor rRNA by guide RNAs
The nucleolus is a ribosome-producing factory
The function of the nucleolus in ribosome and other ribonucleoprotein synthesis
From RNA to Protein
mRNP remodeling occurs during nucleocytoplasmic transport
The Nuclear RNP is distinct from the Cytoplasmic RNP
mRNA encode the protein sequence : The Genetic Code
The three possible reading frames in protein synthesis
tRNA molecules match amino acids to codons in mRNA
Wobble base-pairing between codons and anticodons
tRNAs are covalently modified before they exit the nucleus
tRNAs can contain “unusual” nucleotides
Specific enzymes couple each amino acid to its appropriate tRNA molecule
Structure of the aminoacyl-tRNA linkage: A high energy linkage used
to drive protein synthesis
The genetic code is translated by means of two adaptors that act one
after another
Editing by RNA synthetases ensures accuracy
The recognition of a tRNA molecule by its aminoacyl-tRNA synthetase
The incorporation of an amino acid into a protein
Ribosomes
The RNA message is decoded on ribosomes
A comparison of the structures of prokaryotic and eukaryotic
ribosomes
The RNA-binding sites in the ribosome
Text
Translating an mRNA molecule
Elongation factors drive translation forward
The elongation cycle
The elongation cycle
The elongation cycle - tRNA movements
The elongation cycle - The ribosome ratchet
The elongation cycle - The ribosome ratchet
Structure of the rRNAs in the large subunit of a bacterial ribosome,
as determined by x-ray crystallography
Location of the protein components of the bacterial large ribosomal
subunit
The Ribosome is a Ribozyme
The Ribosome is a Ribozyme
The Ribosome is a Ribozyme
A possible reaction mechanism for the peptidyl transferase activity
present in the large ribosomal subunit
Structure of the L15 protein in the large subunit of the bacterial
ribosome
Translational Initiation: a critical node of gene regulation
mRNA: Defined by two unique co-transcriptional
modifications
mRNA: Defined by two unique co-transcriptional
modifications
5’ cap
m7Gppp
mRNA: Defined by two unique co-transcriptional
modifications
5’ cap
3’ poly(A) tail
m7Gppp
AAAAAAAA
m7Gppp
AAAAAAAA
G
E
m7Gppp
B
A
eIF-4F
AAAAAAAA
G
E
m7Gppp
B
A
eIF-4F
PAB
AAAAAAAA
PAB physically communicates with eIF4G
G
E
m7Gppp
B
A
eIF-4F
PAB
AAAAAAAA
End-to-end communication may allow multiple rounds of
reinitiation
AA
A
PAB
AA
AA
A
7m Gp
pp
eIF4F
AAAAA
A
Ribosomes
The initiation phase of protein synthesis in eukaryotes
The final phase of protein
synthesis - Translational
Termination
The structure of a human translation release factor (eRF1) and its
resemblance to a tRNA molecule
Proteins are made on polyribosomes
Steps in the creation of a functional protein
The co-translational folding of a protein