Fibrinogen superfamily proteins: Key regulators in hepatic disorders

Figure 1 Structure of fibrinogen superfamily proteins. A: Fibrinogen (FG) is a soluble glycoprotein with a molecular weight of 340 kDa, comprising three distinct subunits: Aα, Bβ, and Gγ chains; B: The monomeric form of FG-like protein (FGL) 1 contains an N-terminal C-terminal FG-like domain and a C-terminal FG-related domain. Two identical 34 kDa subunits assemble into a functional dimer via disulfide linkages; C: Membrane-bound FGL2 is classified as a type II transmembrane glycoprotein, featuring an intracellular domain at its N-terminus, a transmembrane segment, and an extracellular region at the C-terminus; D: Soluble FGL2 exhibits structural polymorphism, existing as both monomeric and tetrameric forms. Initially, monomers dimerize through disulfide bonds, followed by further association into tetramers via additional covalent bridges. FG: Fibrinogen; FGL1: Fibrinogen-like protein 1; mFGL2: Membrane-bound fibrinogen-like protein 2; sFGL2: Soluble Fibrinogen-like protein 2.