Integrinin

Integrins are a family of cell surface receptors that play a crucial role in cell adhesion. They are heterodimeric transmembrane proteins, meaning each integrin is composed of two distinct subunits: an alpha (α) subunit and a beta (β) subunit. There are at least 18 known α subunits and 8 known β subunits in mammals, which combine in various ways to form over 24 different integrin heterodimers. These heterodimers are expressed on the surface of most cells and are involved in a wide range of biological processes.

The primary function of integrins is to mediate cell-cell and cell-extracellular matrix (ECM) adhesion. They bind to specific ligands, which can be molecules in the ECM such as collagen, fibronectin, and laminin, or molecules on the surface of other cells. This binding is often dependent on the presence of divalent cations like magnesium or manganese. Upon ligand binding, integrins undergo conformational changes that transmit signals across the cell membrane, both inside and outside the cell. This signaling is bidirectional, a process known as inside-out and outside-in signaling.

Inside-out signaling involves intracellular events that alter integrin conformation and increase their affinity for extracellular ligands. Outside-in signaling refers to the transmission of information from the ECM or other cells through the integrin into the cell, influencing cellular behavior such as cell growth, survival, differentiation, and migration. Because of their central role in these processes, integrins are critical for tissue development, wound healing, immune responses, and blood clotting. Dysregulation of integrin function is implicated in various diseases, including cancer metastasis and inflammatory disorders, making them important targets for therapeutic intervention.