allosteriska

Allosteriska, or allosteric regulation, describes a system in which a protein’s activity is modulated by the binding of an effector molecule at a site distinct from the active site. This allosteric site is typically located on a multi-subunit protein or a protein with a flexible domain, and binding changes the protein’s conformation to alter its catalytic activity or binding affinity. Allosteric regulation enables rapid, reversible control of biochemical pathways in response to cellular conditions.

Key features include cooperative effects, conformational coupling between sites, and the ability to switch between different activity states. Two classic models describe allostery: the Monod-Wyman-Changeux (MWC) concerted model, which posits that proteins exist in equilibrium between at least two states (T and R) and ligand binding shifts the distribution; and the Koshland-Némethy-Filmer (KNF) sequential model, which allows state changes to propagate locally upon ligand binding. Many allosteric proteins are oligomeric, which facilitates communication between subunits.

Examples of allosteric regulation include hemoglobin’s oxygen binding, regulated by effectors such as 2,3-bisphosphoglycerate and pH; the enzyme aspartate transcarbamoylase (ATCase), controlled by ATP and CTP; and phosphofructokinase (PFK), regulated by ATP, ADP, AMP, and other metabolites. Allosteric effectors can act as activators or inhibitors and can produce feedback control in metabolic pathways.

Allosteric regulation has broad relevance in physiology and pharmacology. Therapeutic strategies increasingly target allosteric sites to modulate protein activity with potentially greater specificity and fewer off-target effects than active-site inhibitors.