Keadaan di mana ikatan suatu substrat, produk, atau efektor lain pada suatu subunit dari enzim multi-subunit pada lokasi (lokasi alosterik) bukan pada lokasi fungsional yang mengubah konformasi dan fungsinya. Kata sifat: allosteric.
The site to which the effector binds is termed the allosteric site. Allosteric sites allow effectors to bind to the protein, often resulting in a conformational change involving protein dynamics. Effectors that enhance the protein's activity are referred to as allosteric activators, whereas those that decrease the protein's activity are called allosteric inhibitors.
Allosteric regulations are a natural example of control loops, such as feedback from downstream products or feedforward from upstream substrates. Long-range allostery is especially important in cell signaling. Allosteric regulation is also particularly important in the cell's ability to adjust enzyme activity.
The term allostery comes from the Greek allos (ἄλλος), "other," and stereos (στερεὀς), "solid (object)." This is in reference to the fact that the regulatory site of an allosteric protein is physically distinct from its active site.