P (peptidyl) site

Definition

The P (peptidyl) site is one of three binding sites on the ribosome essential for protein synthesis. It holds the tRNA carrying the growing polypeptide chain during translation.

5 Must Know Facts For Your Next Test

1. The P site is located in the large subunit of the ribosome.
2. It is also referred to as the peptidyl-tRNA binding site.
3. The P site works closely with the A (aminoacyl) and E (exit) sites during translation.
4. During elongation, new amino acids are added to the growing chain at this site.
5. tRNA moves from the A site to the P site after peptide bond formation.

Related terms

A (aminoacyl) site:

A binding site on the ribosome that holds tRNA carrying an amino acid to be added to the polypeptide chain.

E (exit) site:

A binding site on the ribosome through which tRNAs exit after their amino acids have been added to the polypeptide chain.

Translation:

The process by which a protein is synthesized from mRNA using ribosomes, tRNAs, and various enzymatic factors.