Eukaryotic Translation Flashcards
What is involved in the general sequence of mRNA processing in Eukaryotes?
Transcription
Addition of 5’ cap
Addition of poly(A) tail
Intron splicing with the spliceosome
Whole ribosome in eukaryotes is…
80S
Small subunit is 40S
Large subunit is 60S
Do eukaryotes have more protein synthesis factors?
Yes they do
Subunit binding is controoled by…
eIF6
Which factors prevent premature subunit binding?
eIF3
What occurs in the initiation step in eukaryotes that is different to prokaryotes?
tRNA binds to small subunit before mRNA does.
What binds the mRNA to the small subunit of the ribosome?
First, the cap-binding complex is fixated onto the 40S unit which allows 5’ cap end of the mRNA strand to lock onto to the small subunit.
What is the Kozak sequence?
Preferred sequence context for a translation start codon.
GCCAUGG
Why is the 2’ RNA unwinded by the eIF4A?
This is ATP dependent
This unwinding allows the 40S subunit to slide along the mRNA molecule to allows scanning to occur.
When tRNA finds the start codon, what occurs?
GTP hydrolyses from eIF2 and the inititation complex is released.
This allows the 60S subunit to latch onto the exposed space above the 40S subunit.
What plays the same role as EF-Tu in eukaryotes?
EF1 (alpha) complex along with GTP/GDP + Pi
GTP hydrolyses once the aa-tRNA has binded. Is this true?
Yes it is true as this leads to the regeneration of a new EF1 alpha GTP.
Peptidyl transferase?
Cata;yses peptide bond formation between adjacent amino acids on a ribosome.
Does translocation occur at the same time as elongation?
As each AA is added to the ribosome, the ribosome moves up one triplet code as the tRNA are shifted from right to left to occupy the E and the P sites.
eRF1 is responsible for…
recognising the stop codons along the mRNA strand. They bind to these codons and influence the ribosome to cleave the bond between the tRNA and the growing chain of amino acids.
