Integrin αIIb-β3

3D Model

Integrins are widely expressed glycoprotein adhesion molecules critical for processes involving cell to cell contact and migration. Platelets are covered in specific forms of integrin which coordinate activati0n and aggregation during clotting. Historically, before their structure was known, integrins were referred to as glycoproteins and in medical literature the name has stuck, even though the nomenclature is ambiguous. As a result, antiplatelet drugs that target these proteins are called GPIIb/IIIa inhibitors despite acting on integrin αIIb-β3. The α and β refer to distinct protein chains that combine to form the integrin complex. This is an example of tertiary structures, the alpha and beta chains, combining to make a quaternary structure, the functional integrin. Mutations in glycoprotein genes lead to large platelets with defective adhesion and aggregation resulting in increased bleeding time. See the fibrinogen model for drugs to block unwanted clotting.