Integrin belongs to the integrin family. It is a type of heteroadhesive cell adhesion molecule that is ubiquitous on the surface of vertebrate cells and depends on Ca2+ or Mg2+. And adhesion, it has the role of linking the external effect of the cell with the internal structure of the cell.
Figure 1. Cartoon representation of the molecular structure of protein registered with 1jv2 code.
Integrin is a transmembrane heterodimer that consists of two non-covalently bound transmembrane subunits, the alpha and beta subunits. The extracellular spherical domain is a head with a lipid bilayer layer of about 20nm. The head can bind to extracellular matrix proteins, and the intracellular tail is connected to actin. The two subunits of the integrin, the α and β chains, are glycosylated and are held together by non-covalent bonds. Binding of integrins to matrix proteins requires the participation of divalent cations, such as Ca2+, Mg2+. Some extracellular matrix proteins are recognized by multiple integrins.
As a transmembrane linker, integrin acts as a two-way connection between the extracellular matrix and the intracellular actin skeleton, connecting the extracellular matrix with the intracellular matrix network as a whole. Integrins also have the effect of transmitting extracellular signals into cells. When the extracellular domain of an integrin is combined with an extracellular ligand (such as fibronectin or laminin), it will induce a structural change in the end of the integrin intracellular domain, which in turn will cause a change in configuration. The interaction between the end of the cytoplasmic domain of integrin and adjacent proteins is changed, as does focal adhesion kinase (FAK). As a result, FAK can cause phosphorylation of some proteins and cause a cascade of signal amplification. In some cases, this response can trigger the expression of some genes. Signal transduction involving integrins (and other cell surface molecules) affects many cell behaviors, including exercise, growth, and even cell survival. There are two types of integrin recognition and binding to adhesion proteins in the extracellular matrix: one is binding to the RGD region, and the other does not require the RGD region.
Figure 2. Protein structure of focal adhesion kinase.
Alpha Integrin Proteins
Figure 3. Protein structure of alpha integrin 1.
Figure 4. Structure of the ITGA2 protein.
Figure 5. Structure of the ITGA11 protein.
Figure 6. Structure of the ITGA2B protein.
Figure 7. Cartoon representation of the molecular structure of protein registered with 1jv2 code.
CD49a is the integrin alpha subunit. It accounts for half of the α1β1 integrin duplex.
Integrin alpha-2 or CD49b (differentiation cluster 49b) is a protein encoded by the CD49b gene in humans. The CD49b protein is an integrin alpha subunit. It forms half of the α2β1 integrin duplex. Integrins are heterodimeric integral membrane glycoproteins composed of a unique alpha chain and a common beta chain. They are found in a variety of cell types, including T cells (NKT cells), NK cells, fibroblasts, and platelets. Integrins are not only involved in cell adhesion, but also in cell surface-mediated signaling. The expression of CD49b and LAG-3 has been used to identify type 1 regulatory (Tr1) cells. DX5 is a monoclonal antibody that binds to CD49b.
CD11c is also called integrin, αX (complement component 3 receptor 4 subunit) (ITGAX), which is a gene encoding CD11c. CD11c is an integrin αX chain protein. Integrins are heterodimeric integral membrane proteins composed of alpha and beta chains. The protein binds to the β2 chain (ITGB2) to form a leukocyte-specific integrin, called inactivated C3b (iC3b) receptor 4 (CR4). The αXβ2 complex appears to overlap the properties of αMβ2 integrin in the phagocytosis of neutrophils and monocytes to stimulated endothelial cells and complement-coated particles. CD11c is a type I transmembrane protein that is present at high levels in most human dendritic cells, as well as monocytes, macrophages, neutrophils, and some B cells, and can induce cell activation. And help trigger neutrophil respiratory bursts. It is expressed in hairy cell leukemia, acute non-lymphocytic leukemia, and some B-cell chronic lymphocytic leukemias.
Integrin α-IIb is a protein encoded by the ITGA2B gene. ITGA2B, also known as CD41, encodes the integrin alpha chain 2b. Integrins are heterodimeric integral membrane proteins composed of alpha and beta chains. Alpha chain 2b undergoes post-translational cleavage, producing disulfide-linked disulfide-linked light and heavy chains, forming fibrinogen receptors expressed in platelets, which receptors play a key role in coagulation. Mutations that interfere with this effect can cause thrombosis. In addition to adhesion, integrins are also involved in cell surface-mediated signaling.
Integrin alpha-V is a protein that in humans is encoded by the ITGAV gene.
Integrin alpha M (ITGAM) is one protein subunit that forms heterodimeric integrin alpha-M beta-2 (αMβ2) molecule, also known as macrophage-1 antigen (Mac-1) or complement receptor 3 (CR3). ITGAM is also known as CR3A, and cluster of differentiation molecule 11B (CD11B). The second chain of αMβ2 is the common integrin β2 subunit known as CD18, and integrin αMβ2 thus belongs to the β2 subfamily (or leukocyte) integrins.
Figure 8. Structure of the ITGAM protein.
Xiong JP.; et al. Crystal structure of the extracellular segment of integrin alpha Vbeta3. Science. 2001, 294 (5541): 339–45.