Fibronectin
- OMIM: 135600
- UniProt: P02751
Fibronectin (from Latin: fibra for " fiber"; nexus for " linking " ) is a glycoprotein of the extracellular matrix, which in many physiological processes, including tissue repair, embryogenesis, hemostasis as well as in cell migration and adhesion is an important plays role. It also promotes a non-specific opsonic the binding of antigens to phagocytic cells. It also comes intracellularly before ( in platelets ). Mutations in FN1 gene can lead to a glomerulopathy ( GFND2 ) or Ehlers -Danlos syndrome type X.
Structure
Fibronectin is a heterodimer of two polypeptide chains of rod-shaped, which are held together near the C-terminal end by disulfide bonds. So far, more than 20 different isoforms have been found, which are generated by alternative splicing of mRNA of a single gene. A single fibronectin polypeptide (~ 230 kDa ) is composed of a plurality of domains ( approximately 40-90 amino acids ) which are grouped according to their homology to the structure types I, II, and III. To its functions (see below ) to fulfill contains fibronectin binding regions for fibrin, heparin, and collagen and cell binding region.
Expression and function
Fibronectin is substantially formed in two locations, and two kinds:
- In the liver, the soluble variant of the plasma fibronectin is synthesized and released into the blood plasma. Where it plays an important role in wound healing and blood clotting in which fibronectin is incorporated into the fibrin clot in order to accelerate the binding of keratinocytes, fibroblasts and cells of the immune system tissue regeneration.
- Fibroblasts as well as chondrocytes, endothelial cells and macrophages, however, form insoluble fibronectin, which they store in the extracellular matrix. This fibronectin has one hand a kind of bridge between collagen fibrils and other molecules of the extracellular matrix, on the other hand, it serves as an adhesion molecule for different cells during this hike. The ability to merge cells with the extracellular matrix, fibronectin initially brought the name of a cell adhesive.
In recent research, there is evidence that fibronectin may also be involved in the attachment of metastases.
Fetal fibronectin
Fetal fibronectin ( fFN ) is one of the isoforms of fibronectin. It is secreted by the trophoblast and serves the bonding of chorion and decidua.
While the detection of fetal fibronectin is considered normal in early pregnancy, it may the later stages of pregnancy show an impending birth or premature birth.