Areas of DNA
which consist mostly of the base pair
sequence CGCGCGCG (alternating cytosine
and guanine nucleotide
bases) that are usually found upstream
of many gene
s and are thought to help regulate gene expression
. They are often methylate
d (have methyl group
s attached to the DNA segments). These act as promoter region
s in genes, thus the "p" in their name.
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.