Question

what is the role of P site and A site?

Answer 1

The ribosome has three sites: the A site, the P site and the E site.

• In the A site – (The aminoacyl site) a tRNA charged with an amino acid (aminoacyl-tRNA) is presented to the messenger RNA (mRNA) being translated. The A site is the point of entry for the aminoacyl tRNA The aminoacyl-tRNA in the A-site functions as the acceptor for the growing protein during peptide bond formation.
• The P site (peptidyl site) carries the growing peptide chain attached as a peptidyl-tRNA complex. The P site is where the peptidyl tRNA is formed in the ribosome. The P-site is also known as puromycin sensitive site. Puromycin is an antibiotic which shows similarities with a part of aminoacyl-tRNA.
• The E site (Exit site) contains empty tRNAs on their way out of the ribosome. The E site is the ribosomal site that harbouring decylated tRNA on transit out from the ribosome after it gives its amino acid to the growing peptide chain.