TRANSLATIONAL CONTROL OF PROTEIN SYNTHESIS IN A CELL-FREE SYSTEM DIRECTED BY A POLYCISTRONIC VIRAL RNA.

Observations with RNA isolated from the RNA virus indicate that regulation of protein synthesis occurs during translation. At least three electrophoretically separable proteins, one of which lacks histidine, appear as a result of adding purified viral RNA to a cell-free extract of Escherichia coli. This establishes that the RNA contains at least three cistrons. Comparison of the kinetics of appearance of the proteins that do and do not contain histidine reveals a control mechanism which determines the temporal order and the frequency of translation of each cistron. Such translational controls at the stage of message use provide additional devices for regulating protein synthesis which can supplement those functioning at the transcription step where genetic messages are produced.