macroglobulin


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macroglobulin

 [mak″ro-glob´u-lin]
a protein (globulin) of high molecular weight, in the range of 1,000,000; observed in the blood in a number of diseases.
α2-macroglobulin a plasma protein that inhibits a wide variety of proteolytic enzymes, including trypsin, plasmin, thrombin, kallikrein, and chymotrypsin, by entrapping and reducing the accessibility of their functional sites to large molecules. Written also alpha2-macroglobulin.

macroglobulin

(măk′rō-glŏb′yə-lĭn)
n.
A plasma globulin of high molecular weight.

macroglobulin

Any large serum protein, usually ≥ 400 kD—e.g., IgM (900 kD), α2-macroglobulin (820 kD). Macroglobulins are detected by sharp peaks on a simple zone electrophoresis, usually in the gamma region; because of the differing charges on the radicals, the electrophoretic mobility (pI) on the agar may shift and monoclonal spikes may occur in the beta or, less commonly, in the alpha region.

macroglobulin

Any large serum protein, usually ≥ 400 kD–eg, IgM–900 kD, α2-macroglobulin–820 kD; macroglobulins are detected by sharp peaks on a simple zone electrophoresis, usually in the γ-region

macroglobulin

See IgM.
References in periodicals archive ?
Alpha (2)- macroglobulin: a novel cytochemical marker characterizing Preneoplastic and neoplastic rat liver lesions negative for hitherto Established cytochemical markers.
It's unclear how the identified mutation, a small deletion, affects alpha2 macroglobulin. It may hamper the protein's ability to bind other proteins.
Three most recognizable of them are [alpha]1 anti chymotrypsin (ACT), [alpha]1 macroglobulin & [alpha]1 protein inhibitor.
The values are traceable to the matrix material USNRP 12-0575C for albumin (ALB), ceruloplasmin (CER), [[alpha].sub.2] macroglobulin (A2M), haptoglobin (HPT), complement 3c (C3c), complement 4 (C4), IgA, IgG, and IgM and to the First International Standard CRP 85/ 506 for C-reactive protein (CRP).
[8] Nonstandard abbreviations: CRM, certified reference material; TTR, transthyretin (prealbumin); AAG, [[alpha].sub.1] acid glycoprotein (orosomucoid); AAT, [[alpha].sub.1] antitrypsin ([[alpha].sub.1]-protease inhibitor); TRF, transferrin; ACT, [[alpha].sub.1] antichymotrypsin; ALB, albumin; CER, ceruloplasmin; A2M, [[alpha].sub.2] macroglobulin; HPT, haptoglobin; C3c, complement 3c; C4, complement 4; CRP, C-reactive protein; B2M, [[beta].sub.2]-microglobulin; TF, transfer factor.
Currently the most reliable serologic assessment of liver fibrosis uses a panel of 5 markers: [alpha]2 macroglobulin (a2M), haptoglobin, apolipoprotein [alpha]1 , y-glutamyl transpeptidase, and bilirubin (4).
Analysis was performed with an Immage instrument (Beckman-Coulter) for the following 22 analytes: albumin, prealbumin (PAB), [[alpha].sub.1]-acid glycoprotein, al-antitrypsin, [[alpha].sub.2] macroglobulin (AMG), ([[beta].sub.2] microglobulin, factor B, C1 inhibitor, C1q, C3, C4, C5, ceruloplasmin (CERU), IgA, IgG, IgGj, IgGz, IgG3, Ig[G.sub.4], IgM, and [kappa] and [lambda] light chains.
Contributing variables could include the release of proteolytic enzymes during blood clotting and the formation of complexes between fPSA and [[alpha].sub.2] macroglobulin (17).
Several predictive indices using more commonly performed laboratory tests have been proposed, including the Forns index (8), which uses age, [gamma]-glutamyl transferase (GGT), cholesterol, platelet count, and prothrombin time; the APRI index, which uses aspartate aminotransferase activity and platelet count (9); and the Fibrotest/Actitest (10), which uses GGT, bilirubin, [[alpha].sub.2] macroglobulin, haptoglobin, and apolipoprotein [A.sub.1] (along with alanine aminotransferase for the Actitest).