Alpha-2-Macroglobulin (a2M)

Alpha2-macroglobulin is a major serum protein with diverse functions, including inhibition of protease activity and binding of growth factors, cytokines, and disease factors. It is also a panproteinase inhibitor that is found immunohistochemically in neuritic plaques.

Alpha-2-macroglobulin is able to inactivate an enormous variety of proteinases (including serine-, cysteine-, aspartic- and metalloproteinases). Alpha-2-macroglobulin has in its structure a 35 aminoacid "bait" region. Proteinases binding and cleaving the bait region become bound to alpha2M. The proteinase-α2M complex is recognised by macrophage receptors and cleared from the system.