Phosphorylase: a biological transducer.

A transducer is a device that receives energy from one system and transmits it, often in a different form, to another. Glycogen phosphorylase receives information from the cell or organism in the form of metabolic signals. The energy associated with the binding of these ligand signals is integrated and transmitted at an atomic level, allowing precise adjustment of the enzymatic activity. Understanding this elegant allosteric control has required several different approaches, but the structural requirements of allostery are being defined.