Recombinant Mouse Integrin alpha 3 beta 1/VLA-3 Protein, CF

Integrin alpha 3 beta 1, also known as VLA-3 (Very Late Antigen 3), is a member of the integrin family, beta 1 subfamily, of cell membrane adhesion molecules (1-3). It is a non-covalent heterodimer composed of two type I transmembrane glycoprotein subunits, a 130-150 kDa alpha 3 (CD49c) subunit and a 130-140 kDa beta 1 (CD29) subunit. Integrin alpha 3 only associates with the beta 1 subunit. It is synthesized as a 1051 amino acid (aa) precursor that undergoes proteolytic cleavage to generate a disulfide-linked 110 kDa, 842 aa extracellular heavy chain and a 30 kDa, 176 aa TM/cytoplasmic light chain (1, 4, 5, 6). The heavy chain contains seven 60 aa repeats that fold into a propeller-like structure (7). Sequences involving the first three repeats are associated with ligand binding (1). Mouse alpha 3 heavy chain is 88% aa identical to human heavy chain. Unlike the alpha 3 subunit, the mouse beta 1 subunit does not undergo proteolytic cleavage (8). The molecule contains a 708 aa extracellular region, a 23 aa TM segment, and a 47 aa cytoplasmic domain. The extracellular region contains one von Willebrand factor-like A domain and four cysteine-rich repeats. Mouse beta 1 extracellular domain shares 93% and 98% aa sequence identity with human and rat beta 1, respectively. Integrin alpha 3 beta 1 is known to bind fibronectin, collagen, and laminin-1, 5, 8, 10 and 11 (1). It also binds tetraspanins such as CD9, CD63 and CD151. CD151 binding may actually stabilize it, enabling it to bind to additional factors (9).