Recombinant Human Integrin alpha 1 beta 1 Protein, CF

Integrin alpha1 beta1, also called VLA1 is the only alpha1 integrin family adhesion receptor, one of twelve integrins that share the beta1 subunit, and one of four collagen‑binding integrins (1‑5). It is the non‑covalent heterodimer of 190‑210 kDa alpha1 (CD49a) and 130 kDa beta1 (CD29) type I transmembrane glycoprotein subunits. It is found on cells including activated T cells, B cells, monocytes, vascular smooth muscle cells, osteoblasts and adipocytes (2, 6‑8). The alpha1 extracellular domain (ECD) contains an I (inserted) domain which includes the ligand binding site (2, 4). The beta1 ECD contains a vWFA domain, which participates in binding (3). Each subunit then has a transmembrane sequence and a short cytoplasmic tail. Divalent cations and intracellular (inside-out) signaling convert the dimer from the folded, inactive form to its most active, extended conformation (1, 2). The 1113 amino acid (aa) human alpha1 extracellular domain (ECD) shares 88‑92% aa sequence identity with mouse, rat, canine, bovine and equine alpha1, while the 708 aa human beta1 ECD shares 92‑96% aa sequence identity with rat, bovine, mouse, and feline beta1. Potential alpha1 splice variants show two or four aa substitutions for aa 765‑1179. alpha1 beta1 preferentially binds collagens I, IV, VI, XIII and XVI, but also binds laminin (4‑10). alpha1 beta1 is reported to down‑regulate EGF R signaling, increase expression of caveolin-1, reduce production of reactive oxygen species, regulate collagen expression, control MMP collagenase and gelatinase activity, and mediate the renal basement membrane disorder Alport syndrome (10‑12). These effects may begin by alpha1 beta1 binding of caveolin-1, initiating signaling pathways that involve the phosphatase TC-PTP, kinases ERK and p38, and the transcription factor PPAR-gamma (10‑13). alpha1 beta1 down‑regulates MMP-mediated angiostatin formation, enhancing tumor vascularization (8). alpha1 beta1-null mice are deficient in fibroblast collagen IV and laminin-mediated cell spreading and migration, show defects in bone healing, and are resistant to Alport renal fibrosis (9‑11, 14). When expressed in the same epithelial cells, alpha1 beta1 negatively regulates integrin alpha2 beta1‑mediated cell adhesion and migration (15).