Induction of four proteins in eukaryotic cells by kethoxal bis(thiosemicarbazone).

Kethoxal bis(thiosemicarbazone) induces the synthesis of four proteins (100 000, 70 000, 35 000 and 25 000 daltons) in normal chick embryo cells. The 70 000 dalton species is produced at the fastest rate 2 hr after exposure to the compound. Pulse-chase experiments revealed neither precursors nor products of these proteins and both actinomycin and cycloheximide inhibited their synthesis. Neither of the two substituents of the inducer, kethoxal or thiosemicarbazide, were active. The four proteins were induced in several other species, but human cells produced only three proteins (100 000, 70 000 and a different 30 000 dalton form).