What is "ficolin"

n. (context protein English) Any of a pair of binding proteins that have domains related to either collagen or fibrinogen

Ficolins (Fi+Col+Lin) are a group of oligomeric lectins with subunits consisting of both collagen (Col)-like long thin stretches and fibrinogen (Fi)-like globular domains with lectin (Lin) activity usually specific for N-acetylglucosamine (GlcNAc). Like collectins (Col+lectin) such as mannan-binding lectin, ficolins are secreted, lectin-type pattern recognition receptors, and similarly activate the lectin pathway of complement activation.

Examples of human ficolins include:

1. FCN1
2. FCN2
3. FCN3

Immunologist Jeak L. Ding and her team found that natural IgG (nIgG; a non-specific immunoglobulin of adaptive immunity) is not quiescent, but plays a crucial role in immediate immune defense by collaborating with ficolin (an innate immune protein).