Recombinant Human Integrin alpha 9 beta 1 Protein, CF

Integrin alpha9 beta1 is one of twelve integrin family adhesion receptors that share the beta1 (CD29) subunit (1-3). It is the non-covalent heterodimer of 150 kDa alpha9 and 130 kDa beta1 type I transmembrane glycoprotein subunits (3). The alpha9 extracellular domain (ECD) contains an N-terminal beta-propeller structure, followed by domains termed thigh, calf-1 and calf-2 (2). The beta1 ECD contains a vWFA domain, which interacts with the alpha9 beta-propeller to form a binding domain when the dimer is in the active, extended and open conformation. The 952 amino acid (aa) human alpha9 extracellular domain (ECD) shares 89-93% aa sequence identity with mouse, rat, canine, bovine and equine alpha9, while the 708 aa human beta1 ECD shares 92-96% aa sequence identity with rat, bovine, mouse, and feline beta1. Each subunit has a transmembrane sequence and a short cytoplasmic tail which, for alpha9, contains binding sites for paxillin and SSAT (spermine/spermidine-N-acetyltransferase) (4, 5). Integrin alpha9 beta1 inhibits cell spreading via signaling through paxillin (4). SSAT interaction with alpha9 beta1 allows catalysis that lifts spermine/spermidine inhibition of KIR potassium channels and enhances cell migration (5). Lymphangiogenic vascular endothelia growth factors VEGF-C and VEGF-D are ligands for Integrin alpha9 beta1 (6, 7) Genetic deletion of mouse alpha9 beta1 results in a fatal chylothorax due to abnormal lymphatic development (8). Integrin alpha9 beta1 interacts in cis with G-CSF R and enhances its signals, contributing to granulopoiesis (9). It also binds VCAM-1, which promotes neutrophil trans endothelial migration, and delays apoptosis (10, 11). Other ligands for alpha9 beta1 include tenascin, osteopontin, nerve growth factor, and most members of the ADAM family (12, 14).