Fibronectin
| Fibronectin | ||
|---|---|---|
| Properties of human protein | ||
| Mass / length primary structure | 2355 amino acids | |
| Isoforms | 15th | |
| Identifier | ||
| Gene name | FN1 | |
| External IDs | ||
Fibronectin (from the Latin: fibra for "fiber"; nexus for "linking") is a glycoprotein of the extracellular matrix , which in many physiological processes, including tissue repair, the embryogenesis , the hemostasis as well as in cell migration and -adhäsion an important Role play. As a non-specific opsonin , it also promotes the binding of antigens to phagocytes . It is also found intracellularly (in platelets). Mutations in the FN1 gene can lead to glomerulopathy (GFND2) or Ehlers-Danlos syndrome type X.
structure
Fibronectin is a heterodimer consisting of two rod-shaped polypeptide chains which are held together by disulfide bridges near the C-terminal end . So far, more than 20 different isoforms have been found that are generated by alternative splicing of the mRNA of a single gene . A single fibronectin polypeptide chain (~ 230 kDa ) consists of a large number of domains (approx. 40–90 amino acids ), which are divided into structural types I, II and III based on their homology . In order to be able to fulfill its functions (see below), fibronectin contains binding regions for fibrin , heparin and collagen as well as a cell binding region .
Expression and function
Fibronectin is essentially formed in two places and two ways:
- The soluble variant of plasma fibronectin is synthesized in the liver and released into the blood plasma . There it plays an important role in wound healing and blood coagulation, where fibronectin is incorporated into the fibrin clot in order to accelerate tissue regeneration by binding keratinocytes , fibroblasts and cells of the immune system .
- Fibroblasts, as well as chondrocytes , endothelial cells and macrophages , on the other hand, form insoluble fibronectin , which they store in the extracellular matrix . On the one hand, this fibronectin has a kind of bridging function between collagen fibrils and other molecules of the extracellular matrix ; on the other hand, it serves as an adhesion molecule for various cells while they are migrating . The ability to connect cells with the extracellular matrix initially gave fibronectin the name of cell glue .
In recent research there is evidence that fibronectin may also be involved in metastasis attachment .
Fetal fibronectin
Fetal fibronectin (fFN) is one of the isoforms of fibronectin. It is secreted by the trophoblasts and serves to glue the chorion and decidua together .
While in the early pregnancy detection of fetal fibronectin is considered to be normal, it can later stages of pregnancy impending birth or preterm Show.
Individual evidence
- ↑ Vaheri A Fibronectin (cold-insoluble globulin): role in defense. Switzerland Med Wochenschr. 1980 Oct 4; 110 (40): 1437-1440.
- ↑ UniProt P02751
- ↑ Wolfgang Heinrich The importance of transvaginal cervical sonography for the prediction of premature birth in the low-risk and high-risk collective habilitation thesis Berlin 2003.
- ↑ Fetal fibronectin test on Majoclinic.com
Web links
- Fibronectin. In: Online Mendelian Inheritance in Man . (English)
- reactome: Exocytosis of fibronectin
- Geiger, B. and Horwitz, R./reactome: Integrin cell surface interactions . doi : 10.3180 / REACT_13552.1