Ficolin-1 also known as M-Ficolin is a pattern recognition molecule of the lectin complement activation pathway. It is expressed mostly in monocytes, nuetrophils and in type II alveolar epithelial cells. Ficolin-1 is detected on the surface of circulating monocytes but is not present in the plasma. Ficolin-1 has a 28 aa signal sequence, an N-terminal collagen domain and a C-terminal fibrinogen-like (FBG) domain that contain a calcium binding site and a potential N-glycosylation site.