Binding site

In biochemistry, a binding site is a region on a protein, DNA, or RNA to which specific other molecules and ions &mdash; in this context collectively called ligands, or more specifically, protein ligands &mdash; form a chemical bond.

The term saturation refers to the fraction of total binding sites that are occupied at any given time.

When more than one type of ligand can bind to a binding site, competition ensues.

An equilibrium exists between unbound ligands and bound ligands.

Binding sites also exhibit chemical specificity, a measure of the types of ligands that will bond, and affinity, which is a measure of the strength of the chemical bond.

A more specific type of binding site is the transcription factor binding site, present on DNA.