REACTION STEPS OF POLYPEPTIDE SYNTHESIS IN RIBOSOMES MECHANISMS OF PROTEIN SYNTHESIS .10.

1. The results communicated in the ample recent literature on cell-free protein synthesis from amino acyl-tRNA support the ribosomal three-site-model (cf. Fig. 3). The possibility that one or two substrate binding sites precede the donor- and acceptor-sites remains to be investigated (cf. Fig. 11). 2. It is shown in which sequence, and on which sites the individual steps of initiation, elongation and termination could occur. 3. The functions in these steps of factors found in bacteria and higher organisms are compared as far as possible. 4. Checking of correspondence between codon and anticodon appears to follow principles of basepairing in three ribosomal sites; these checking devices amplify specificity and stability above the level to be expected on the basis of simple triplet-pairing, and consist partly at least of protein. © 1968 Springer-Verlag.