P-site

The P-site (for peptidyl) is the second binding site for tRNA in the ribosome. The other two sites are the A-site (aminoacyl), which is the first binding site in the ribosome, and the E-site (exit), the third. During protein translation, the P-site holds the tRNA which is linked to the growing polypeptide chain. When a stop codon is reached, the peptidyl-tRNA bond of the tRNA located in the P-site is cleaved releasing the newly synthesized protein.[1] During the translocation step of the elongation phase, the mRNA is advanced by one codon, coupled to movement of the tRNAs from the ribosomal A to P and P to E sites, catalyzed by elongation factor EF-G.[2]

  1. ^ Lodish, Harvey (2013). Molecular cell biology (Seventh ed.). New York: Worth Publ. pp. 141–143. ISBN 978-1-4292-3413-9.
  2. ^ Rodnina, MV; Savelsbergh, A; Katunin, VI; Wintermeyer, W (2 January 1997). "Hydrolysis of GTP by elongation factor G drives tRNA movement on the ribosome". Nature. 385 (6611): 37–41. Bibcode:1997Natur.385...37R. doi:10.1038/385037a0. PMID 8985244.