Step I translation

[aspiringmd1015]

FA states that for initiation, initiation factor plus the help of GTP helps bind the initiator trna to the 40s ribosome, and then the initiating factor gets released when the mrna and 60s binds to form the full complex. My questoin is, how does the intiator trna know where to bind if the mrna isnt there already? shouldnt the mrna be bound first?

 

[Transposony]

That's why it's called an initiator tRNA since it practically goes and looks for the mRNA's initiator codon.

1. There is formation of preinitiation complex by binding of a ternary complex consisting of met-tRNAi , GTP, and eIF-2 to the 40S ribosome (43S initiation complex).
2. This complex scans the mRNA to look for AUG initiator codon and this binding with mRNA causes the formation of 48S initiation complex.
3. Binding of of the 48S initiation complex with the 60S ribosomal subunit forms the 80S initiation complex.
All these steps require various initiation factors, binding proteins and GTP.

 

[slz1900]

This seems to be the paper where it is discussed. There is no way that this would be asked about on step, though.

 

[aspiringmd1015]

That's why it's called an initiator tRNA since it practically goes and looks for the mRNA's initiator codon.

1. There is formation of preinitiation complex by binding of a ternary complex consisting of met-tRNAi , GTP, and eIF-2 to the 40S ribosome (43S initiation complex).
2. This complex scans the mRNA to look for AUG initiator codon and this binding with mRNA causes the formation of 48S initiation complex.
3. Binding of of the 48S initiation complex with the 60S ribosomal subunit forms the 80S initiation complex.
All these steps require various initiation factors, binding proteins and GTP.

if its looking for and finding the intitiator mrna codon is on the ribosome, that would mean the mrna is already there on the ribosome correct?

 

[aspiringmd1015]

what is wild-type transcription factor??