what is fibronectin's role in communication with the extracellular matrix?
Fibronectin is a high-molecular weight (~440kDa) glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. Similar to integrins, fibronectin binds extracellular matrix components such as collagen, fibrin, and heparan sulfate proteoglycans (e.g. syndecans). Fibronectin exists as a protein dimer, consisting of two nearly identical monomers linked by a pair of disulfide bonds. The fibronectin protein is produced from a single gene, but alternative splicing of its pre-mRNA leads to the creation of several isoforms. Two types of fibronectin are present in vertebrates: 1  soluble plasma fibronectin (formerly called cold-insoluble globulin, or CIg) is a major protein component of blood plasma (300 Î¼g/ml) and is produced in the liver by hepatocytes.  insoluble cellular fibronectin is a major component of the extracellular matrix.