Translation Flashcards
Translation in Prokaryotes Step 1
Translation in Prokaryote Step 2
Translation in Prokaryote Step 3
Closed Loop Model of Eukaryotic Translation
Translocation of Ribosome Down the mRNA transcript
What are the three roles of the release factor
Hydrolysis of the terminal peptidyl bond,
release of the polypeptide and tRNA
dissociation of the ribosomal subunits
Puromycin
premature chain termination by acting as an analog of aa-tRNA
ribosome can’t translate which leads to dissociation
tetracyclins
blocks the A site on 30S subunit and inhibits binding of aminoacyl tRNAs
Chloramphenicol
inhibits peptidyl transferase (prokaryotes)
cycloheximide
inhibits peptidyl transfease in eukaryotes
streptomycin
inhibits initiation and causes misreading of mRNA in prokaryotes
diptheria toxin
inactivates eukaryotic eEF3
Ricin
inactivate the 60S subunit of the eukaryotic ribosome
What are consensus properties of signal sequences directed to the ER?
stretch of hydrophobic amino acids
one or more positively charged residues preceding hydrophobic sequence
some polar amino acids and short side chains near cleavage site
What are the 8 steps that take a protein from free ribosomes to the ER?
The ER Gylcosylation pathway
Core oligosaccharide is attached to dolichol phosphate and core is built up on cytosolic face of ER
oligosaccharide translocated across ER
other mannose or glucose residues may be added to oligo
In N-linked proteins transferase moves oligosaccharide to asn residue
oligosaccharide is modified and dolichol phosphate carrier molecule is recycled
Transport to Mitochondria
N-Terminal Signal Sequence bound by HSP 70 and MSF
(mostly ser thr and basic residues)
Precursor is delivered to receptor and then transferred inside via mHSP70 and electrochemical potential
signal sequence is removed and protein is refolded
Transport to the Nucleus
Polyubiquitination
Protein targeting in Prokaryotes
ER Glycosylation (picture)
