Using this system, Kornberg made the major discovery that transmission of gene regulatory signals to the RNA polymerase machinery is accomplished by an additional protein complex that they dubbed Mediator.
A partir deste sistema, Kornberg fixo o importante descubrimento de que a transmisión dos sinais reguladores de expresión dos xenes á maquinaria da ARN polimerase se leva a cabo mediante un complexo proteico adicional que denominaron mediador.