Recombinant Human Fibronectin Fragment 3 Protein, CF

Fibronectin (FN) is a large modular glycoprotein that is found as a polymeric fibrillar network in the extracellular matrix (ECM) and as soluble disulfide-linked dimeric protomers in plasma and other body fluids (1, 2). The protein subunit is made up of three types of homologous structural motifs termed FN type I, type II, and type III repeats (3 - 5). Alternative splicing generates multiple isoforms of Fibronectin which may have insertions of extra type III domains (EDA and EDB) or alteration of the type III connecting segment (IIICS) (5). Fibronectin is a ligand for many molecules including fibrin, heparin, chondroitin sulfate, collagen/gelatin, and integrins. It is involved in multiple cellular processes such as cell adhesion/migration, blood clotting, morphogenesis, tissue repair, and cell signaling. Fibronectin functions are mediated by the insoluble polymeric fibrils in the ECM. Conversion of soluble Fibronectin to Fibronectin fibrils in the ECM is initiated by binding to cell surface integrins, resulting in exposure of cryptic epitopes necessary for polymerization (1). FN1.3 includes the EDB plus type III domains #8 - 13 and the initial region of domain 14. These domains facilitate association with heparin, myocilin, ApoA, and integrins alpha 5 beta 1 and alpha V beta 3 (6 - 10). The tilt angle between type III domains #9 and #10 (which contains an RGD motif) determines the affinity of interaction with these integrins, suggesting how structural differences between fibrillar and soluble Fibronectin may influence their function (10). Within FN1.3, human Fibronectin shares 97% and 92% aa sequence identity with mouse and rat Fibronectin, respectively.