Translation in PKs Flashcards
Initiation is GTP independent or Dependent?`
Dependent
Association of Small and Large sub0unit of Ribosome happens at?
Ribosome Binding Site
At RBS _____ sequence present.
Shine Dalgaro sequence
Initiating Codin
AUG
GUG
UUG
Initiating amino acid in E.coli
N-Formyl Methionine
Initiating amino acid in Archae Bacteria
Methionine
Shine Dalgaro Sequence
Short ntd. seq.
7 ntds.: 5’ AGGAGGU 3’
Purine rich
Slight sequece variation
Shine Dalgaro Sequence Located at?
3-10 ntds. upstream of the Start codon.
Complementary sequence of Shine Dalgar is present at?
@ 3’ end of 16S rRNA
Translational Coupling
It refers to the mechanism by which the translation of one mRNA molecule is linked to the translation of another, often leading to coordinated expression of genes that may be functionally related.
N-Formyl Methionine and Methionine
Initiation Codon (IC) is same for both
But tRNA is different
tRNA for N-Formyl Methionine
tRNA^fmet
tRNA for Methionine
tRNA^met
Enzyme for N-Formyl Methionine
Met tRNA Synthetase: Amino acylates bot tRNA with Met
What promotes active translation?
High Complementarity b/w RBS & rRNA
Proper spacing b/w RBS and Start Codon
Amino acid binds with tRNA with?
Ester bond
If an ORF lacks RBS, will they be translated. Yes or No?
Yes
Transformylase
Transfer formy group from
N^10 Formyl Tetrahydrofolate to amino group of Met.
which is more selective?
Transformylase or Met-tRNA synthetase
Transformylase
Functions of added formyl?
Prevent fmet from entering the interior position in polypeptide.
allow it to bind at initiation site
Extra GC Sequence and single CA sequence is present on?
Anticodon arm of tRNAi^met
is it necessary that the first peotide will always be Fmet, as tRNA^fmet incorporated first?
No
which enzyme removes the formyl group f amino terminus from the polypeptide?
Deformylase
Aminopeptidases
often removes the amino-terminal methionine and additional to-three amino acids
Initiation Factors
IF1
IF2
IF3
Polypeptide synthesized from nitochondria and chloroplast ribosomes begin with ____________?
N-Formylmethionine.
This suggests that mitochondria and chloroplast are originated from the bacterial ancestors.
Binary complex of IF
IF2 + GTP
Ternary Complex of IF
IF2 + GTP + tRNAi^fmet
Steps?
30S + IF1 + IF3
fmet-tRNA + IF2 + GTP
what inhibits 30S & 50S SUBUNITS FROM COMBINING prematurely?
IF3
IF3 promotes?
mRNA binding to the 30S subunit, and occupy that region which will become the E-Site
what does IF1 do?
it binds to the ‘A’ site, and prevent binding of tRNA during initiation
mRNA is bound by____?
both GTP bound IF2 and fmet-tRNA^fmet
what part of tRNA pairs with mRNA?
Anticodon
Elongation Factors?
- EF-Tu: GTP Binding protein &
GTPase - EF-Ts: Regenerate EF-TI
- EF-G: GTP Binding protein &
GTPase
Binary Complex of EF?
EF-Tu-GTP
Ternary Complex of EF?
EF-Tu-GTP+tRNA^aa
3 sub phases of elongation?
- Decoding : By EF-TU
- Transpeptidation: By 50S-23S rRNA
- Translocation: By EF-G
Decoding?
when amino acyl tRNA enters at ‘A’ site, performed by EF-Tu
Transpeptidation?
Amino acid present on the ‘P’ site added to the a.a present on the ‘A’ site.
Peptidyl transferase activity
when Amino acid present on the ‘P’ site added to the a.a present on the ‘A’ site.
Translocation?
Movement of Ribosome.
Translocation results into conversion of ‘P’ site into ‘E’ site and ‘A’ site into ‘P’.
And new ‘A’ site will be formed.
Which EF act as a GEF?
EF-Ts
Active form of EF-Tu
EF-TU—–GTP
Inactive form of EF-Tu
EF-TU—–GDP
