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Alpha 2-macroglobulin
Alpha-2 macroglobulin (abbreviated α2M or A2M) is a large plasma protein found in the blood. It is produced by the liver, and is a major component of the alpha-2 band in protein electrophoresis. Additional recommended knowledge
StructureAlpha-2 macroglobulin is compose of four identical subunits bound together by -S-S- bonds. FunctionAlpha-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 α2M. The proteinase-α2M complex is recognised by macrophage receptors and cleared from the system. It functions as an inhibitor of coagulation by inhibiting thrombin.[1] It functions as an inhibitor of fibrinolysis by inhibiting plasmin: DiseaseAlpha-2 macroglobulin levels are increased in nephrotic syndrome, a condition wherein the kidneys start to leak out some of the smaller blood proteins. Because of its size, α2-macroglobulin is retained in the bloodstream. Increased production of all proteins means α2-macroglobulin concentration increases. This increase has little adverse effect on the health, but is used as a diagnostic clue. Longstanding chronic renal failure can lead to amyloid by alpha-2 macroglobulin (see main article: amyloid). A common variant (29.5%) (polymorphism) of α2-macroglobulin leads to increased risk of Alzheimer's disease,[2][3] although the mechanism is unknown. α-2 macroglobulin binds to and removes the active forms of the gelatinase (MMP-2 and MMP-9) from the circulation via scavenger receptors on the phagocytes. References
Categories: Genes on chromosome 12 | Acute phase proteins |
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Alpha_2-macroglobulin". A list of authors is available in Wikipedia. |