Effect of preincubation in the cold on poly(U)-dependent polyphenylalanine synthesis in a cell-free rat liver system.

Preincubation of a cell-free poly(Phe) synthesis system in the cold results in a manifold stimulation of the polyphenylalanine synthesis. This stimulatory effect can be observed only if ribosomal subunits, poly(U), Mg++ and cytosolic fraction are present in the reaction mixture during cold pretreatment. This effect is abolished if the samples are preincubated at 37 degrees C before the cold treatment probably because of an inactivation of protein factors present in the cytosolic fraction.