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
genes and are thought to help regulate
gene expression. They are often
methylated (have
methyl groups attached to the DNA segments). These act as
promoter regions 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.