Markedly Different Effects of Monovalent Cations on the Efficiency of Gene Expression.

The effect of monovalent cations on a cell-free transcription-translation (TX-TL) system is examined using a luciferase assay. It is found that the potency for all ions analyzed here is in the order Rb +  > K +  > Cs +  > Na +  ≈ Li +  > (CH 3 ) 4 N + , where Rb + is most efficient at promoting TX-TL and the ions of Li + , Na + , and (CH 3 ) 4 N + exhibit an inhibitory effect. Similar promotion/inhibition effects are observed for cell-free TL alone with an mRNA template.