enhancer definition

<molecular biology> A DNA sequence, present in the genomes of higher eukaryotes and of various animal viruses, which can increase the transcription of genes into messenger RNA.

These control element frequently found 5' to the start site of a gene, when bound by a specific transcription factor, enhance the levels of expression of the gene, but are not sufficient alone to cause expression.

Distinguished from a promoter, that is alone sufficient to cause expression of the gene when bound, in practice, the two terms merge.

Enhancers usually can function in either orientation and at various distances from a promoter.

Compare: promoter.

(03 Jul )

Genetic elements important in the function of a specific promoter.

Origin: M.E. Enhauncen, raise, increase, fr. O. Fr. Enhaucier, fr. L.L. Inalto, fr. Altus, high, + -er, agent suffix

<molecular biology> A nucleotide sequence, located as many as several thousand base pairs away in either direction from the target gene, which enhances transcription of that gene.

(14 Nov 1997)

<molecular biology, technique> Technique for mapping gene expression patterns, classically in Drosophila. A transposon element carrying a reporter gene (usually _ galactosidase), linked to a very weak promoter, is induced to jump within the genome. If the P element re inserts within the sphere of influence of promoters and enhancers of some (random) gene, then reporter gene is also expressed in a similar tissue specific manner. Usually, many lines of flies carrying such random insertions are studied, if a line shows interesting patterns of expression, it can be possible to clone the gene of interest.

This entry appears with permission from the Dictionary of Cell and Molecular Biology