Number of Initiation Factor 1 IF1 molecules per ribosome

Value 0.25 molecules/ribosome
Organism Bacteria Escherichia coli
Reference Bremer, H., Dennis, P. P. (1996) Modulation of chemical composition and other parameters of the cell by growth rate. Neidhardt, et al. eds. Escherichia coli and Salmonella typhimurium: Cellular and Molecular Biology, 2nd ed. chapter 97 Table 4 Table - link
Primary Source Howe JG, Hershey JW. Initiation factor and ribosome levels are coordinately controlled in Escherichia coli growing at different rates. J Biol Chem. 1983 Feb 10258(3):1954-9
Method Cells were grown in media containing [35S]sulfate and different carbon sources, and harvested during mid-exponential phase after about 10 generations of balanced growth. Initiation factors (IF), elongation factors (EF), and a number of ribosomal proteins were identified unambiguously in gel patterns following two-dimensional polyacrylamide gel electrophoresis.
Comments IF1 associates with the 30S ribosomal subunit in the A site and prevents an aminoacyl-tRNA from entering. It modulates IF2 binding to the ribosome by increasing its affinity. It may also prevent the 50S subunit from binding, stopping the formation of the 70S subunit. It also contains a ß-domain fold common for nucleic acid binding proteins.
Entered by Uri M
ID 104062