FN1

Fibronectin type 1 domain
FN1
SMART accession number:SM00058
Description: One of three types of internal repeat within the plasma protein, fibronectin. Found also in coagulation factor XII, HGF activator and tissue-type plasminogen activator. In t-PA and fibronectin, this domain type contributes to fibrin-binding.
Interpro abstract (IPR000083):

Fibronectin type I repeats are one of the three repeats found in the fibronectin protein. Fibronectin is a plasma protein that binds cell surfaces and various compounds including collagen, fibrin, heparin, DNA, and actin. Type I domain (FN1) is approximately 40 residues in length. Four conserved cysteines are involved in disulphide bonds. The 3D structure of the FN1 domain has been determined [(PUBMED:2112232), (PUBMED:1602484), (PUBMED:7582899)]. It consists of two antiparallel beta-sheets, first a double-stranded one, that is linked by a disulphide bond to a triple-stranded beta-sheet. The second conserved disulphide bridge links the C-terminal adjacent strands of the domain.

In human tissue plasminogen activator chain A the FN1 domain together with the following epidermal growth factor (EGF)-like domain are involved in fibrin-binding [(PUBMED:1900516)]. It has been suggested that these two modules form a single structural and functional unit [(PUBMED:7582899)]. The two domains keep their specific tertiary structure, but interact intimately to bury a hydrophobic core; the inter-module linker makes up the third strand of the EGF-module's major beta-sheet.

GO component:extracellular region (GO:0005576)
Family alignment:
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There are 4741 FN1 domains in 570 proteins in SMART's nrdb database.

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