ABSTRACT
Ribosome recycling is a process which dissociates the post-termination complexes (post-TC) consisting of mRNA-bound ribosomes harbouring deacylated tRNA(s). Ribosome recycling factor (RRF), and elongation factor G (EFG) participate in this crucial process to free the ribosomal subunits for a new round of translation. We discuss the over-all pathway of ribosome recycling in eubacteria with especial reference to the important role of the initiation factor 3 (IF3) in this process. Depending on the step(s) at which IF3 function is implicated, three models have been proposed. In model 1, RRF and EFG dissociate the post-TCs into the 50S and 30S subunits, mRNA and tRNA(s). In this model, IF3, which binds to the 30S subunit, merely keeps the dissociated subunits apart by its anti-association activity. In model 2, RRF and EFG separate the 50S subunit from the post-TC. IF3 then dissociates the remaining complex of mRNA, tRNA and the 30S subunit, and keeps the ribosomal subunits apart from each other. However, in model 3, both the genetic and biochemical evidence support a more active role for IF3 even at the step of dissociation of the post-TC by RRF and EFG into the 50S and 30S subunits.
Subject(s)
Models, Genetic , Peptide Chain Termination, Translational , Prokaryotic Initiation Factor-3/chemistry , Protein Subunits/metabolism , RNA, Messenger/metabolism , RNA, Transfer/metabolism , Ribosomes/metabolismABSTRACT
Serum pro-collagen III and liver function tests were estimated in 20 healthy subjects and 71 patients with chronic liver disease in a trial to find out its correlation with clinical, laboratory and histological parameters as well as its diagnostic value. From the results obtained, it was concluded that serum P III NP may be a good marker of liver fibrosis and may be used in differentiating fibrotic liver diseases from those with no or minimal fibrosis and may be a good prognostic clinical marker in the assessment of clinical severity of the disease