Question

How does a bacterial ribosome distinguish between an initiation AUG and an AUG

for a methione in the middle of a protein, and does it make a difference?

Answer 1

Bacterial ribosme has a 16S rRNA which has region that binds to the Delgano and Shine sequence of the mRNA which is first binding site of the initiation AUG, before the complete assembling of fMet and ribosome.

Once the assembling of ribosome and FMet copleted and initiate making protein all other AUG sequence bind to tRNA for a methionine in the middle of a protein.

It matters because it prevent fMET from being incorporate other than initiation site with the help of formy group on the amino Met of methionine.