FGL2 is a 439 amino acid secreted protein that is similar to the β- and γ-chains of fibrinogen. The carboxyl-terminus of the encoded protein consists of the fibrinogen-related domains (FRED). The encoded protein forms a tetrameric complex which is stabilized by interchain disulfide bonds.

This protein may play a role in physiologic functions at mucosal sites.Fgl2 is a protein that exhibits pleiotropic effects within the body and is an important immune regulator of both innate and adaptive responses. The protein exists as both a type II transmembrane protein found on the surface of macrophages and endothelial cells and can be constitutively secreted by both CD4+ and CD8+ T cells.