POST-TRANSLATIONAL MODIFICATION OF ESCHERICHIA-COLI RIBOSOMAL-PROTEIN S6

Escherichia coli has multiple forms of ribosomal protein S6, differing in number of glutamyl residues at the C-terminal end. Three forms are revealed when crude cell extracts are fractionated by a two-dimensional gel electrophoresis technique. Pulse-chase experiments show that the shortes and most alkaline form of S6 is the first to appear. In about one doubling time this form reaches equilibrium with the two other forms of S6, implicating the existance of an enzyme, which adds glutamic acid residues to S6. We show that the relative levels of these three S6 forms are not affected by the growth rate of the culture. © 1979 Springer-Verlag.