||Bacteria Escherichia coli
||Kim YE, Hipp MS, Bracher A, Hayer-Hartl M, Hartl FU. Molecular chaperone functions in protein folding and proteostasis. Annu Rev Biochem. 201382:323-55. doi: 10.1146/annurev-biochem-060208-092442. p.331 caption to figure 4B & p.332 left column bottom paragraphPubMed ID23746257
|| Kaiser CM, Chang H-C, Agashe VR, Lakshmipathy SK, Etchells SA, et al. 2006. Real-time observation of trigger factor function on translating ribosomes. Nature 444: 455–60 DOI: 10.1038/nature05225PubMed ID17051157
||P.331 caption to figure 4B: "TF reaction cycle: Free TF exists in the cytosol as a dimer in rapid equilibrium with monomers. Monomeric TF binds to ribosomes with translating nascent chains. Hydrophobic sequence motifs in the nascent chain regulate TF-nascent chain interaction. Binding to the elongating nascent chain may persist as TF dissociates from the ribosome (with t1/2 ∼ 10 s) (primary source), allowing a second TF molecule to bind to the ribosome at the polypeptide exit site. Concurrent with release from TF, the newly synthesized polypeptide folds into its native state or is transferred to downstream chaperones." P.332 left column bottom paragraph: "Cells contain an excess of TF compared with ribosomes, the non-ribosome-bound fraction is in rapid monomer-dimer equilibrium (Figure 4b) (primary source 63, ref 94). TF monomer aids de novo folding through ATP-independent cycles of binding and release from both the ribosome and the nascent chain. Binding to the ribosome (mean residence time of ∼10–15 s) is a prerequisite for interaction with the nascent chain. The disposition of the bound peptide to bury hydrophobic regions during folding likely drives the eventual release of TF from the nascent chain. Accordingly, TF slows hydrophobic chain collapse and delays cotranslational folding (refs 37, 95, 96)."