Integrin alpha 3 beta 1/VLA-3 Products

Description

VLA-3 (Very Late Antigen 3) is a member of the integrin family, beta 1 subfamily, of cell membrane adhesion molecules (1-3). Integrins are nondisulfide-linked transmembrane (TM) heterodimers that contain an alpha - and beta -subunit (1). VLA-3 is composed of an alpha 3 and beta 1 subunit. The alpha 3/CD49c subunit is a 130-150 kDa type I TM glycoprotein. It only associates with the beta 1 integrin subunit. It is synthesized as a 1051 amino acid (aa) precursor that undergoes proteolytic cleavage to generate a disulfide-linked 110 kDa, 843 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). The light chain has two cytoplasmic alternate splice forms. The A form cytoplasmic domain is 52 aa, while the B form cytoplasmic domain is 37 aa (5). Human alpha 3 heavy chain is 88% aa identical to mouse heavy chain. The human beta 1/CD29 subunit is a 130-140 kDa type I transmembrane glycoprotein (8). Unlike the alpha -subunit, it does not undergo proteolytic cleavage. 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. The cytoplasimc domain shows five alternate splice forms (A, B, C1, C2 and D), all which vary by 12 to 48 amino acids (9, 10). Although the functions of all are unclear, the B isoform appears to be dominant negative to the A isoform (11). Human beta 1 extracellular domain is 92%, 94%, 93% and 96% aa identical to the extracellular regions of beta 1 in rat, bovine, mouse and feline, respectively. VLA-3 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 VLA-3, enabling it to bind to additional factors (12).

Bioinformatics

Uniprot	P26006 (Integrin alpha 3) & P05556 (Integrin beta 1)
Product By Gene ID	3675
Alternate Names	Integrin alpha 3 beta 1 VLA3 VLA-3