A temperature-sensitive suppressor enabling the manipulation of the level of individual proteins in intact cells.

A temperature-sensitive suppressor strain of E. coli has been isolated and characterized. The properties of the mutant indicate a strong potential for its use in biochemical and genetic work. In particular, the mutant makes possible the variation of the intracellular concentration of selected protein, permitting an evaluation of its role in cell growth and biochemistry. The mutant also permits the selective radiochemical labeling of proteins in vivo for in vitro identification and analysis. The utilization of the mutant for these and other applications is discussed.