Trans-acting

In the field of molecular biology, trans-acting generally means "acting from a different molecule" ("i.e.", intermolecular). It may be considered the opposite of cis-acting which generally means "acting from the same molecule" ("i.e.", intramolecular).

In the context of transcription regulation, a trans-acting element is usually a DNA sequence that contains a gene. This gene codes for a protein (or microRNA or other diffusible molecule) that will be used in the regulation of another target gene. [cite book
last = Watson
first = James D.
coauthors = Caudy, Amy A, Myers, Richard M., Witkowski, Jan A.
authorlink = James D. Watson
title = Recombinant DNA: Genes and Genomes - A Short Course
publisher = Cold Spring Harbor Press
date = 2007
pages = 57-58
isbn = 0-7167-2866-4 ] The trans-acting gene may be on the same chromosome as the target gene, but the activity is via the intermediary protein or RNA that it encodes. Cis-acting elements, on the other hand, do not code for protein or RNA. Both the trans-acting gene and the protein/RNA that it encodes are said to "act in trans" on the target gene.

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