Alpha 2-macroglobulin
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
| Identifiers | |
|---|---|
| Symbol | A2M |
| Entrez | 2 |
| HUGO | 7 |
| OMIM | 103950 |
| RefSeq | NM_000014 |
| UniProt | P01023 |
| Other data | |
| Locus | Chr. 12 p13.31 |
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.
Structure
Alpha-2 macroglobulin is compose of four identical subunits bound together by -S-S- bonds.
Function
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 α2M. The proteinase-α2M complex is recognised by macrophage receptors and cleared from the system.
It functions as an inhibitor of coagulation:
Disease
Alpha-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,[1][2] 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
External links
- alpha+2-Macroglobulin at the US National Library of Medicine Medical Subject Headings (MeSH)