FCN1

Extracellular lectin, which acts as a pattern recognition receptor that initiates the lectin pathway of the complement system, a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system. Specifically recognizes and binds carbohydrates on the pathogen surface, activating the MASP1 serine protease and initiating the proteolytic cascade of the lectin complement pathway. 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. May also activate monocytes through a G protein-coupled receptor, FFAR2, inducing the secretion of interleukin-8/IL-8..

Function from UniProtKB (O00602), read 2026-09-23. CC BY 4.0.