ID #2417

So I know the release factor binding to the A site is what makes the polypeptide disengage from the the top of the tRNA, but where does that polypeptide chain go after it is released? Also, what is the release factor? Just a stop codon?

The release factor is a protein that is just the right shape to fit into the A site when it is time to finish translation. The release factor is not a stop codon itself, but a region of the protein interacts with the stop codon found on the mRNA. Then, the release factor tricks the peptidyl transferase portion of the ribosome into thinking that the next tRNA is present. When the peptidyl transferase tries to move the polypeptide chain onto the next tRNA, there is nothing to attach it to, and the polypeptide is released. 
After its release, the polypeptide chain is considered a protein or at least a subunit of a protein. Where it goes depends on the job of the protein. 

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