ABSTRACT
Once thought to be primarily inert structural scaffolding, studies have shown that the extracellular matrix (ECM) is a complex structure containing many glycoproteins. Biochemical characterization of ECM components has resulted in the identification of a series of proteins that to a certain degree share structural and functional features. The existence of extensive structural information including primary sequence data for fibronectin has enabled investigators to compare fibronectins from normal developmental stages and from various pathological conditions. The fibrin-binding affinity of the aminoterminal domain is relatively high, whereas the heparin-binding affinity of this domain is relatively low. The collagen-binding domain also contains two additional important biochemical features. A small domain located at the carboxyterminal has been found to contain the interchain disulfide bond that joins the subunits of the fibronectin dimer. Plasma fibronectin was originally described as a nonthrombin-coagulable by-product of fibrinogen-rich plasma fractions. The glycosylation of synovial fibronectin differs from that of plasma fibronectin in several respects.
