Recombinant Mouse Integrin alpha V beta 5 Protein, CF

Integrin  alpha V beta 5 is one of five alpha V integrins and the only known beta 5 integrin (1‑3). The non‑covalent heterodimer of 170 kDa alpha V and 100‑110 kDa beta 5 integrin type I transmembrane glycoprotein subunits is expressed on a wide variety of cell types including keratinocytes, fibroblasts, adhesive monocytes, embryonic stem cells, and select endothelium and epithelium (4‑8). alpha V beta 5 binds ligands containing an RGD motif, notably vitronectin (1‑10). The 958 aa mouse alpha V extracellular domain (ECD) shares 92‑95% aa sequence identity with human and bovine alpha V, while the 696 aa mouse beta 5 ECD shares 97%, 91% and 91% aa sequence identity with rat, human and bovine beta 5, respectively. The alpha V ECD contains an N‑terminal beta ‑propeller structure, followed by domains termed thigh, calf‑1 and calf‑2 (1). The 799 aa beta 5 contains a vWFA domain within the ECD, which interacts with the alpha V beta ‑propeller to form a binding domain. Each subunit has a transmembrane sequence and a short cytoplasmic tail. Potential beta 5 isoforms include a 691 aa form with an alternate start site at aa 109, a 958 aa form with an alternate N‑terminus, and a 795 aa form with an alternate C‑terminus. Post‑translational modifications, such as proteolytic cleavage of the alpha V subunit or phosphorylation of the beta 5 cytoplasmic tail, can increase endocytic turnover of the alpha V beta 5 protein and/or promote cell migration (7‑10). Growth factors that increase PKC activity, such as VEGF or TGF‑ alpha, promote alpha V beta 5-mediated angiogenesis while alpha V beta 3, which may be expressed in the same cell, responds to FGF‑basic and TNF‑ alpha (11). An inhibitor of both down‑regulates tumor angiogenesis (12). During lung inflammation, up‑regulation of alpha V beta 5 on myofibroblasts or infiltrating lymphocytes may contribute to fibrosis by freeing TGF‑ beta from latency (13, 14). On retinal pigment epithelia, alpha V beta 5 is important for normal diurnal phagocytosis of outer rod segments, and contributes to adhesion of retinal cells (15).