Trans-acting factor

A Trans-acting factor is a molecule, generally a protein, whose task is to regulate another molecule, usually by binding to a cis-acting element.

In eukaryotes, transcription factors are trans-acting elements, while in prokaryotes the same can be said of repressors in the operon system.

This short article is of interest to the Molecular and Cellular Biology WikiProject.
You can help Wikipedia by expanding it.