Fcn1
Domain
The fibrinogen C-terminal domain mediates calcium-dependent binding to carbohydrates and tethering to the cell surface in monocytes and granulocytes. The domain undergoes a conformational switch at pH under 6.2, and looses its carbohydrate-binding ability.
Function
Extracellular lectin functioning as a pattern-recognition receptor in innate immunity. Binds the sugar moieties of pathogen-associated molecular patterns (PAMPs) displayed on microbes and activates the lectin pathway of the complement system. May also activate monocytes through a G protein-coupled receptor, FFAR2, inducing the secretion of interleukin-8/IL-8. Binds preferentially to 9-O-acetylated 2-6-linked sialic acid derivatives and to various glycans containing sialic acid engaged in a 2-3 linkage (By similarity).
Sequence Similarities
Belongs to the ficolin lectin family.
Tissue Specificity
Highly expressed in liver and spleen.
Cellular localization
- Secreted
- Cell membrane
- Peripheral membrane protein
- Extracellular side
- Found on the monocyte and granulocyte surface.
Alternative names
Fcna, Fcn1, Ficolin-1, Collagen/fibrinogen domain-containing protein 1, Ficolin-A, Ficolin-alpha, M-ficolin