Two-dimensional analysis of proteins phosphorylated in E. coli cells.

Proteins phosphorylated in Escherichia coli cells were analyzed by the O'Farrell two-dimensional gel technique. Cytoplasmic and ribosomal fractions were studied separately. Double labeling with [32P]orthophosphate and [35S]sulfate followed by selective autoradiographic detection of each radioisotope allowed precise location of 12 major phosphoproteins on the total protein pattern of bacteria. Both the molecular mass and isoelectric point of these phosphoproteins were determined.