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 (PubMed:21037097). 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.
Sequence Similarities
Belongs to the ficolin lectin family.
Tissue Specificity
Peripheral blood leukocytes, monocytes and granulocytes. Also detected in spleen, lung, and thymus, may be due to the presence of tissue macrophages or trapped blood in these tissues. Not detected on lymphocytes.
Cellular localization
- Secreted
- Cell membrane
- Peripheral membrane protein
- Extracellular side
- Found on the monocyte and granulocyte surface (PubMed:20400674).
Alternative names
FCNM, FCN1, Ficolin-1, Collagen/fibrinogen domain-containing protein 1, Ficolin-A, Ficolin-alpha, M-ficolin