IntegrinProteins

Integrins are a large family of cell surface receptors that play a crucial role in cell adhesion, migration, and signaling. They are heterodimeric proteins, meaning each integrin is composed of two distinct subunits, an alpha (α) subunit and a beta (β) subunit, linked non-covalently. There are at least 18 known α subunits and 8 known β subunits in mammals, which can combine in various ways to form over 24 different integrin heterodimers.

These receptors are transmembrane proteins, with one end exposed to the extracellular environment and the other end interacting with the cell's internal cytoskeleton. Extracellularly, integrins bind to a variety of ligands, most notably components of the extracellular matrix (ECM) such as collagen, fibronectin, and laminin. They can also bind to other cell surface molecules and even soluble proteins. This binding is often dependent on the presence of divalent cations like magnesium or manganese.

Intracellularly, integrins link to the actin cytoskeleton through a complex network of adaptor proteins. This physical connection allows integrins to transmit signals from the extracellular environment into the cell, influencing processes such as cell shape, proliferation, differentiation, and survival. This bidirectional signaling, known as inside-out and outside-in signaling, is fundamental to integrin function. Integrins are essential for numerous physiological processes, including embryonic development, wound healing, immune responses, and blood clotting. Dysregulation of integrin function is implicated in various diseases, including cancer metastasis, inflammatory disorders, and fibrotic conditions, making them important therapeutic targets.