The Reverse Side of a Coin: "Factor-Free" Ribosomal Protein Synthesis In Vitro is a Consequence of the In Vivo Proofreading Mechanism

Biomolecules. 2019 Oct 8;9(10):588. doi: 10.3390/biom9100588.


This paper elucidates a close connection between two well-known facts that until now have seemed independent: (i) the quality control ("proofreading") of the emerging amino acid sequence, occurring during the normal, elongation-factor-dependent ribosomal biosynthesis, which is performed by removing those Aa-tRNAs (aminoacyl tRNAs) whose anticodons are not complementary to the exhibited mRNA codons, and (ii) the in vitro discovered existence of the factor-free ribosomal synthesis of polypeptides. It is shown that a biological role of proofreading is played by a process that is exactly opposite to the step of factor-free binding of Aa-tRNA to the ribosome-exposed mRNA: a factor-free removal of that Aa-tRNA whose anticodon is not complementary to the ribosome-exhibited mRNA codon.

Keywords: EFTu; GTP; anticodon-codon recognition; binding of Aa-tRNA; biosynthesis of polypeptides; complementarity; elongation factor Tu; factor-free process; factor-promoted process; free energy; non-complementarity; parallel reactions; proofreading; removal of Aa-tRNA; ribosome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anticodon / metabolism
  • Nucleic Acid Conformation
  • Peptides / genetics
  • Peptides / metabolism*
  • Protein Biosynthesis
  • RNA, Messenger / metabolism
  • RNA, Transfer, Amino Acyl / metabolism*
  • Ribosomes / metabolism*


  • Anticodon
  • Peptides
  • RNA, Messenger
  • RNA, Transfer, Amino Acyl