Antibodies to Alpha 2-Macroglobulin

Alpha 2-Macroglobulin, human

Antibody Host Catalogue No. Size Product Insert
purified IgG Goat GAA2M-IG 10 mg
affinity purified IgG Goat GAA2M-AP 0.5 mg
affinity purified peroxidase conj. IgG Goat GAA2M-APHRP 0.1 mg

Description of Alpha 2-Macroglobulin

Alpha 2-Macroglobulin (α2M) is a large proteinase inhibitor molecule of 718,000 daltons, consisting of 4 identical subunits of 185,000 each. Produced in hepatocytes and macrophages, plasma concentrations of α2M are typically 2 μM in adults, and as high as 6 μM in childhood. α2M has the ability to inhibit most enzymes from the serine, metallo, cysteine and aspartate subclasses. It is not a member of the SERPIN family of inhibitors but belongs to a class of proteins that include pregnancy zone protein (PZP) and the complement proteins C3, C4 and C5. These proteins contain regions of conserved sequence as well as one or more internal β-cysteinyl-γ-glutamyl thiolester bonds, which in the case of α2M are susceptible to cleavage by enzymes or by nucleophilic compounds such as methylamine or ammonium ions. Although the precise nature of the interactions is as yet unknown, it is generally thought that cleavage of a bait region within the α2M molecule by an enzyme leads to a conformational change, which then traps and/or covalently binds the enzyme1,2. The active site of the trapped enzyme is usually still intact and able to cleave small substrates, but is inaccessible to larger natural substrates. The conformational change induced also exposes receptor-binding regions within the molecule, which may be important in the clearance of α2M-enzyme complexes from the circulation. It is thought that the main role of α2M in vivo is that of a “backup” inhibitor and scavenger of proteinases in blood and in tissues3,4, but it has also been reported to participate in other physiological processes, including regulation of immune function1,2.


1. Salvesen G, Pizzo SV; Proteinase Inhibitors: α-Macroglobulins, Serpins and Kunins; in Hemostasis and Thrombosis, 3rd Edition, eds. RW Colman, J Hirsh, VJ Marder and EW Salzman, pp. 241-258, J.B. Lippincott Co., Philadelphia PA, USA, 1994.

2. Barrett J; α2Macroglobulin; Methods in Enzymology, 80, pp 737-754, 1981

Larsson LJ, Neuenschwander DE, Strickland DK; Reaction of Proteinases with α2Macroglobulin: Evidence for Alternate Reaction Pathways in the Inhibition of Trypsin; Biochemistry 28, pp 7636-7643, 1989.

3. Schmidt B, Mitchell L, Ofosu FA, Andrew M; α2Macroglobulin is an Important Progressive Inhibitor of Thrombin in Neonatal and Infant Plasma; Thromb Haemostas 62, pp 1074-1077, 1989.

4. Hoogendoorn H, Toh CH, Nesheim ME, Giles AR; α2Macroglobulin Binds and Inhibits Activated Protein C; Blood 78, pp2283-2290, 1991.

Related Products:

GAA2M-IG Goat anti-human α2M, whole IgG from antiserum

GAA2M-APHRP Goat anti-human α2M, APIgG-peroxidase conjugate