alpha 2-Macroglobulin: ProductsAlpha 2-Macroglobulin (A2M) is an abundant plasma glycoprotein that has structural similarity to other A2M family members including complement components C3, C4 and C5. A2M is a tetramer (720-kDa) of 4 identical subunits (180-kDa) formed by two disulfide bond-linked dimers. It is a general and irreversible protease inhibitor capable of inhibiting all four classes of proteases by a unique trapping mechanism. A2M also binds many cytokines and growth factors. In the brain, A2M binds soluble beta Amyloid. A2M is recognized as a late onset Alzheimers disease gene.