Initiation of the polypeptide chain in the rII B cistron of bacteriophage T4

The internal initiator x of the rII B cistron of bacteriophage T4 (Sarabhai & Brenner, 1967) can be made to initiate protein synthesis in the absence of a nearby terminating triplet by deleting a particular group of 3n nucleotides to its left. This shows that free ribosomes can directly initiate protein synthesis at an internal initiation sequence, when the initiator is in a structurally favorable configuration