At the end of the termination stage in bacteria, the ribosome complex on is still associated with mRNA and a deacylated tRNA, most probably with its acceptor end in the E-site of the 50S subunit and its anticodon end in the P-site of the 30S subunit. During the recycling stage, the ribosomal subunits dissociate from this complex, freeing them to participate in a new round of polypeptide synthesis. In bacteria, this process requires a new translation factor known as the ribosome release factor (RRF).
RRF is an essential protein that was originally thought to bind in the free A-site because its structure is similar to that of tRNA. However, footprinting experiments and cryo-electron microscopy constructs show that instead of binding to the free A-site, RRF binds almost at right angles to this site. EF2•GTP and IF3 somehow assist RRF in disassembling the post termination complex. The details of this disassembly process remain to be determined. Virtually nothing is known about the recycling stage in eukaryotes. Thus far, no eukaryotic counterpart to the bacterial RRF has been discovered. One possibility is that one or more eukaryotic ribosomal proteins assist in recycling SO that a soluble ribosome release factor is not required. Following ribosome disassembly, the small ribosomal subunit is free to interact with the initiation factors to start a new round of polypeptide synthesis.