Research progress in the molecular mechanism of α2-macroglobulin

α 2-Macroglobulin (A2M) is a high-abundance plasma protein with a molecular weight of 720×10³, containing 1451 residues and 11 domains, and was isolated and identified for the first time in 1946. The capture and inhibitory effect on proteases is the classical biological function of A2M. However, A2M can also interact with membrane receptors, cytokines, and growth factors, and act as a molecular chaperone to affect extracellular protein homeostasis so that it is involved in a wide range of physiological and pathological processes such as immunity, inflammation, and degeneration. This article reviews the structural characteristics of A2M, the reported molecular targets, the mechanism of action, and its biological effects in the hope of providing a new line of thought for the functional exploration and clinical applications of A2M.