The subcellular distribution and state of the elongation factor Tu in extracts of Escherichia coli B.

The concentration of elongation factor Tu (EF-Tu) is about 8 times that of ribosomes in extracts of Escherichia coli B grown in glucose-minimal medium. 90% of the EF-Tu is found in the ribosome-free fraction of the cell and 75% of this is free of other macromolecules as judged by chromatography on Sephadex G-100; about 10% is bound to the elongation factor EF-Ts and the remaining 10-15% is eluted from Sephadex G-100 earlier than expected for its molecular weight. Tryptic peptide maps of the three forms of EF-Tu are essentially indistinguishable.