Integrins are α/β heterodimeric adhesion glycoprotein receptors that mediate attachment between cells and extracellular matrix. Integrins bind ECM proteins through their large ectodomain and engage the cytoskeleton via their generally short cytoplasmic tails. Such linkage permits the bi-directional transmission of signals across the plasma membrane.
CHEMICAL STRUCTURE AND IMAGES
When relevant for the function
- Primary structure
- Secondary structure
- Tertiary structure
- Quaternary structure
Protein Aminoacids Percentage
The Protein Aminoacids Percentage gives useful information on the local environment and the metabolic status of the cell (starvation, lack of essential AA, hypoxia)
Protein Aminoacids Percentage (Width 700 px)
SYNTHESIS AND TURNOVER
- Cell signaling and Ligand transport
- Structural proteins
In addition to their mechanical roles in anchorage, integrins transmit chemical signals into the cell (outside-in signaling), providing information on its location, local environment, adhesive state and surrounding matrix. These signals determine cellular responses such as migration, survival, differentiation and motility.
In addition to outside-in signaling, integrins can regulate their affinity for extracellular ligands by undergoing conformational changes in their extracellular domains, that occur in response to signals that affect the integrin cytoplasmic tails (inside-out signaling or activation). The exact nature of these conformational changes remains controversial; it is clear, however, that the packing of the α and β transmembrane domains changes (the domains separate, rotate or change their relative position within the membrane). This is followed by alteration in the ligand-binding site.
Integrins as therapeutic targets: lessons and opportunities, Cox D., Nature, 2010
Outside-in and inside-out signaling require assembly and disassembly of multiprotein complexes that form around the cytoplasmic tails of integrins.
The binding of individual integrins, or small clusters of integrins, to ligand, forms an initial talin-mediated connection between the cytoskeleton and the ECM. These adhesions contribute to the reinforcement of the ECM-cytoskeleton link and to the recruitment of additional cytoskeletal and signaling proteins.
Integrin signalling at a glance, Harburger D. S. and Calderwood D. A., 2009