Allosteric regulation

Allosteric regulation changes a protein’s activity when a molecule binds at a site distinct from its active site, altering the protein’s shape or dynamics.

Allosteric site: A protein site where ligand binding changes activity through effects on another site. It is the binding location that distinguishes allosteric control from active-site binding.
Aspartate transcarbamoylase: An enzyme that catalyzes an early step in pyrimidine nucleotide biosynthesis. Its activity is inhibited by the pathway’s end product, cytidine triphosphate.
Allosteric drug: A drug that binds a protein site distinct from its principal ligand-binding or active site and alters function. These drugs exploit the same remote-site control used in physiological regulation.
Competitive inhibition: Enzyme inhibition in which an inhibitor competes with the substrate for the active site. It acts at the active site rather than through a separate allosteric site.
Ligand (biochemistry): A molecule that binds specifically to a protein or other biological macromolecule. Allosteric regulators are ligands that bind outside the active site.
Conformational change: A change in a protein’s three-dimensional shape without changing its amino-acid sequence. Allosteric binding can shift the protein into shapes with different activity.
Phosphofructokinase-1: A glycolytic enzyme that phosphorylates fructose 6-phosphate to fructose 1,6-bisphosphate. ATP and citrate inhibit it, while AMP and fructose 2,6-bisphosphate activate it.
Allosteric modulator: A ligand that changes a protein’s response to another ligand by binding at a separate site. It can amplify or diminish a protein’s response without occupying its active site.
Uncompetitive inhibition: Enzyme inhibition in which an inhibitor binds only to the enzyme–substrate complex. Its defining feature is state-dependent binding, not necessarily regulation from a remote site.
Active site: The region of an enzyme where substrate binding and catalysis occur. Allosteric sites are defined in relation to this catalytic region.

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