BACKGROUND The Integrins are a family of alpha/betab heterodimeric receptors that mediate dynamic linkages between extracellular adhesion molecules and the intracellular actin cytoskeleton. Integrins are expressed by all multicellular animals, but their diversity varies widely among species; for example, in mammals, 19 alpha and 8 beta subunit genes encode polypeptides that combine to form 25 different receptors. Both Integrin subunits are type I transmembrane proteins with large extracellular and short cytoplasmic domains of 700-1100 and 30-50 residuesrespectively. Integrins are ubiquitously expressed and at physiological conditions, Integrins are highly glycosylated and contain a Ca2+ or Mg2+ ion, which is essential for ligand binding. Integrin receptors are critical for cell attachment to the extracellular matrix (ECM) and this is mediated through integrin-fibronectin, -vitronectin, -collagen and -laminin interactions. Intracellularly, Integrins form adhesion complexes with proteins including talin, vinculin, paxillin and alpha-actinin. They also regulate kinases, such as focal adhesion kinase and Src family kinases, to mediate attachment to the actin cytoskeleton. Integrins also have a significant role in cell signaling and can activate protein kinases involved in the regulation of cell growth, division, survival, differentiation, migration and apoptosis. The beta 1, beta 3, and beta 5 Integrin intracellular domains are sufficient to initiate signal transduction pathways. Furthermore, alternative splicing can regulate the ability of beta integrin intracellular domains to participate in signal transduction. Glycoprotein II/IIIb (alphaIIb/beta3) is an integrin receptor found on the surface of platelets. It is involved in the cross-linking of platelets with fibrin, and so has a vital role in blood clot formation.1
Integrin alpha 5 chain undergoes post-translational cleavage in the extracellular domain to yield disulfide-linked light and heavy chains that join with beta 1 to form a fibronectin receptor. It recognizes the sequence R-G-D in its ligands. Alpha5/beta1 is involved in many cellular processes including cell proliferation and oncogenic transformation, assembly of FN-rich extracellular matrices, cell migration, regulation of gene expression, wound healing, and T cell activation.2 For example, loss of alpha5/beta1 integrin expression and increased alpha3/beta1 integrin expression were associated with the transformed phenotype of fibroblasts. Overexpression of alpha5/beta1 integrin leads to a loss of anchorage-independent growth and reduced tumongenicity in transformed Chinese hamster ovary cells.3 It has also been suggested that a5b1 may play important roles during embryogenesis and differentiation. In addition to adhesion, integrins are known to participate in cell-surface mediated signaling.
1. Schwartz, M.A. & Ginsberg, M.H.: et al: Nature Cell Biol. 4:E65-E68, 2002
2. Yang, J.T. et al: Development 119:1093-1105, 1993
3. Gong, J. et al: Cell Growth Different. 8:83-90, 1993
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Purified recombinant human Integrin alpha-5 fragments expressed in E. coli.
Species & predicted
reactivity ( ):
Weight of protein:
Detects endogenous Integrin alpha-5 proteins without cross-reactivity with other family members.
Store at -20°C, 4°C for frequent use. Avoid repeated freeze-thaw cycles.
*Optimal working dilutions must be determined by end user.