Alpha-1-acidic glycoprotein

From CellBiology

Alpha-1-acidic glycoprotein

Homo sapiens complex locus ORM1 and ORM2, encoding orosomucoid 1 and orosomucoid 2.


  • serum protein, also called orosomucoid
  • monomer about 210 amino acid residues long
  • amino acid sequence has been determined through 192 amino acids
  • Variants have been demonstrated in the blood of normal Caucasians and Japanese (Schmid et al., 1965). Johnson et al. (1969) presented twin and family data supporting the view that 3 phenotypes, SS, FF and FS, are determined by 2 codominant alleles.
  • gene for orosomucoid was assigned to the end of the long arm of chromosome 9
  • Yuasa et al. (1997) noted that in plasma, ORM proteins are presented as a mixture of ORM1 and ORM2 proteins in a molar ratio of 3:1, respectively.
  • inflammatory marker (orosomucoid, tumour necrosis factor-alpha, transforming growth factor-beta, vascular endothelial growth factor and monocyte chemoattractant protein-1) PMID20222150


  • biological function of AGP remains unknown[1]
  • lipocalins - based on its theoretical three-dimensional structure as well as on its ability to bind and transport a large number of basic lipophilic compounds.
  • express a variety of immunological properties that are dependent on or influenced by the composition of its five N-linked glycans.
  • plasma level can rise from about 0.8 to 3 g/L within 24 h following the unset of an acute-phase response
    • acute phase proteins - serum concentration increases in response to systemic tissue injury, inflammation or infection, and these changes in serum protein concentrations have been correlated with increases in hepatic synthesis.
  • expression of the AGP gene is controlled by a combination of the major regulatory mediators
    • glucocorticoids and a cytokine network involving mainly interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF alpha), interleukin-6 and IL-6 related cytokines.



Madame Curie Bioscience Database [Internet]. Austin (TX): Landes Bioscience; 2000 uman α1-Acid Glycoprotein, a Drug Binding and Immunomodulatory Protein


  1. <pubmed>11058758</pubmed>

Reference Abstracts

Alpha-1-acid glycoprotein

Biochim Biophys Acta. 2000 Oct 18;1482(1-2):157-71.

Fournier T, Medjoubi-N N, Porquet D. Source INSERM U427, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris 5 René Descartes, France.


Alpha-1-acid glycoprotein (AGP) or orosomucoid (ORM) is a 41-43-kDa glycoprotein with a pI of 2.8-3.8. The peptide moiety is a single chain of 183 amino acids (human) or 187 amino acids (rat) with two and one disulfide bridges in humans and rats,respectively. The carbohydrate content represents 45% of the molecular weight attached in the form of five to six highly sialylated complex-type-N-linked glycans. AGP is one of the major acute phase proteins in humans, rats, mice and other species. As most acute phase proteins, its serum concentration increases in response to systemic tissue injury, inflammation or infection, and these changes in serum protein concentrations have been correlated with increases in hepatic synthesis. Expression of the AGP gene is controlled by a combination of the major regulatory mediators, i.e. glucocorticoids and a cytokine network involving mainly interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF alpha), interleukin-6 and IL-6 related cytokines. It is now well established that the acute phase response may take place in extra-hepatic cell types, and may be regulated by inflammatory mediators as observed in hepatocytes. The biological function of AGP remains unknown; however,a number of activities of possible physiological significance, such as various immunomodulating effects, have been described. AGP also has the ability to bind and to carry numerous basic and neutral lipophilic drugs from endogenous (steroid hormones) and exogenous origin; one to seven binding sites have been described. AGP can also bind acidic drugs such as phenobarbital. The immunomodulatory as well as the binding activities of AGP have been shown to be mostly dependent on carbohydrate composition. Finally, the use of AGP transgenic animals enabled to address in vivo, functionality of responsive elements and tissue specificity, as well as the effects of drugs that bind to AGP and will be an useful tool to determine the physiological role of AGP.

PMID: 11058758

Comparison of methods for the purification of alpha-1 acid glycoprotein from human plasma

J Biomed Biotechnol. 2011;2011:578207. Epub 2011 Mar 8.

McCurdy TR, Bhakta V, Eltringham-Smith LJ, Gataiance S, Fox-Robichaud AE, Sheffield WP. Source Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.


Alpha-1 acid glycoprotein (AGP) is a highly glycosylated, negatively charged plasma protein suggested to have anti-inflammatory and/or immunomodulatory activities. Purification of AGP could be simplified if methods that exploit its high solubility under chemically harsh conditions could be demonstrated to leave the protein in its native conformation. Procedures involving exposure of AGP to hot phenol or sulphosalicylic acid (SSA) were compared to solely chromatographic methods. Hot phenol-purified AGP was more rapidly cleared from mice in vivo following intravenous injection than chromatographically purified AGP. In contrast, SSA-purified AGP demonstrated an identical in vivo clearance profile and circular dichroism spectrum to chromatographically purified AGP. Similarly, no differences in susceptibility to enzymatic deglycosylation or reactivity with Sambucus nigra lectin were detected between AGP purified via the two methods. Incorporation of the SSA step in the purification scheme for AGP eliminated the need for a large (4 mL resin/mL of plasma) initial chromatographic step and simplified its purification without causing any detectable distortion in the conformation of the protein. Confirmation that this procedure is nondenaturing will simplify AGP purification and investigation of its possible biological roles in laboratory animals.

PMID: 21437215

Development and validation of 14 human serum protein assays on the Roche cobas® c 501

J Clin Lab Anal. 2011;25(1):52-60. doi: 10.1002/jcla.20430.

Ledue TB, Collins MF. Source Foundation for Blood Research, Scarborough, Maine 04074, USA. Abstract Many laboratories rely on dedicated nephelometers and turbidimeters for the measurement of serum proteins. There are, however, a number of chemistry analyzers that offer open channel configurations for end-user applications. We developed and validated 14 human serum protein assays (α(1)-antitrypsin, α(2)-macroglobulin, albumin, apolipoproteins AI and B, complement components 3 and 4, haptoglobin, immunoglobulins A, G, and M, orosomucoid, transferrin, and transthyretin) on the Roche cobas(®) c 501. We obtained excellent precision at low, normal, and high physiologic concentrations of each protein (within-run imprecision CVs ≤2.5%, total imprecision CVs ≤3.6%). Linearity for each method was within 5% of the expected value throughout the calibration range, and method comparison studies to commercial assays from Roche or Siemens were in good agreement (r>0.975). We observed no significant interference from bilirubin (up to 414  mg/l), hemoglobin (up to 8.9  g/l), triglyceride (up to 28  g/l), or rheumatoid factor (up to 3,930 IU/ml). Calibration was stable for at least 14 days. The instrument's small reaction cell allowed us to conserve nearly 60% of our specimen and reagent volume compared with our previous system. These newly developed assays provide precise and accurate results with high throughput, but without the associated cost of a dedicated instrument.

© 2011 Wiley-Liss, Inc.

PMID: 21254244

Increased urinary orosomucoid excretion predicts preeclampsia in pregnant women with pregestational type 1 diabetes

Diabetes Res Clin Pract. 2010 Jul;89(1):16-21. Epub 2010 Apr 14.

Christiansen MS, Hesse D, Ekbom P, Hesse U, Damm P, Hommel E, Feldt-Rasmussen B, Mathiesen E. Source Department of Clinical Biochemistry and Department of Medicine, Amager Hospital, Italiensvej 1, Copenhagen S, Denmark. Abstract AIMS: We evaluated the urinary orosomucoid excretion (UOE) as a biomarker of preeclampsia and preterm delivery in pregnant women with type 1 diabetes.

METHODS: Singleton pregnant women with pregestational type 1 diabetes were included provided one urine sample had been collected before 17 gestational weeks. Serum and urinary orosomucoid were analysed by immunoturbidimetry. Primary outcome measurements were development of preeclampsia (blood pressure>140/90mmHg and proteinuria) and preterm delivery before 37 weeks.

RESULTS: In total 173 women were included. The UOE increased during pregnancy. Preeclampsia developed in 20 women and 65 women delivered preterm. Using logistic regression analysis we found that UOE>1.37mg/l (OR: 6.85 (95% CI: 1.97-23.88; p<0.003)), nulliparity (3.88 (1.10-13.72); p<0.04), systolic blood pressure>120mmHg (4.12 (1.35-12.59); p<0.02) and duration of diabetes>20 years (3.69 (1.18-11.52); p<0.03) independently predicted the development of preeclampsia. Independent predictors of preterm delivery were duration of diabetes and HbA1c>7%. The remaining covariates included in the regression models were BMI, serum creatinine, smoking and microalbuminuria.

CONCLUSIONS: Increased UOE early in pregnancy predicted preeclampsia in women with pregestational type 1 diabetes independently of albuminuria and other known risk factors. No association to preterm delivery was found.

  • Urinary orosomucoid was analysed using a particle-enhanced immunoturbidimetric assay [12] on Cobas Mira and Cobas Integra 700 (Roche, Basel, Switzerland).
  • Serum samples were kept frozen at −20 °C until analysis of orosomucoid (reference range: 0.45–1.17 g/l)

PMID: 20392509

Orosomucoid system: 17 additional orosomucoid variants and proposal for a new nomenclature

Vox Sang. 1993;64(1):47-55.

Yuasa I, Weidinger S, Umetsu K, Suenaga K, Ishimoto G, Eap BC, Duche JC, Baumann P. Source Department of Legal Medicine, Tottori University School of Medicine, Yonago, Japan. Abstract There are two forms of orosomucoid (ORM) in the sera of most individuals. They are encoded by two separate but closely linked loci, ORM1 and ORM2. A number of variants have been identified in various populations. Duplication and nonexpression are also observed in some populations. Thus, the ORM system is very complicated and its nomenclature is very confusing. In order to propose a new nomenclature, ORM variants detected by several laboratories have been compared and characterized by isoelectric focusing (IEF) followed by immunoprinting. A total of 57 different alleles including 17 new ones were identified. The 27 alleles were assigned to the ORM1 locus, and the others to the ORM2 locus. The designations ORM*F1, ORM1*F2, ORM1*S and ORM2*M were adopted for the four common alleles instead of ORM1*1, ORM1*3, ORM1*2 and ORM2*1 (ORM2*A), respectively. The variants were designated alpha numerically according to their relative mobilities after IEF in a pH gradient of 4.5-5.4 with Triton X-100 and glycerol. For the duplicated genes a prefix is added to a combined name of two alleles, e.g. ORM1*dB9S. Silent alleles were named ORM1*Q0 and ORM2*Q0 conventionally. In addition, the effects of diseases to ORM band patterns after IEF are also discussed.

PMID: 8447119

Alpha 1-acid glycoprotein (orosomucoid): pathophysiological changes in glycosylation in relation to its function

Glycoconj J. 1995 Jun;12(3):227-33.

van Dijk W, Havenaar EC, Brinkman-van der Linden EC. Source Department of Medical Chemistry, Faculty of Medicine, Amsterdam, The Netherlands.


The aim of this review is to summarize the research efforts of the last two decades with respect to (i) the determination and characterization of the changes in glycosylation of AGP under various physiological and pathological states; and (ii) the effects of such changes on its possible anti-inflammatory functions. It will become clear that the heterogeneity observed in the glycosylation of AGP in serum, represents various so-called glycoforms of AGP, of which the relative amounts are strictly determined by the (patho) physiological conditions.

PMID: 7496136

Inflammation-induced expression of sialyl Lewis X-containing glycan structures on alpha 1-acid glycoprotein (orosomucoid) in human sera

J Exp Med. 1993 Mar 1;177(3):657-66.

De Graaf TW, Van der Stelt ME, Anbergen MG, van Dijk W. Source Department of Medical Chemistry, Faculty of Medicine, Vrije Universiteit, Amsterdam, The Netherlands.


The glycosylation of the acute phase glycoprotein alpha 1-acid glycoprotein (AGP) in human sera is subject to marked changes during acute inflammation as a result of the cytokine-induced hepatic acute phase reaction. The changes described thus far comprise alterations in the type of branching of the carbohydrate structures as revealed by increased reactivity of AGP with concanavalin A. We now report on acute inflammation-induced increases in alpha 1-->3-fucosylated AGP molecules, as detected by the reactivity of AGP towards the fucose-binding Aleuria aurantia lectin (AAL) in crossed affino-immunoelectrophoresis of human sera. Laparotomy of women, for the removal of benign tumors of the uterus, was used as a model for the development of the hepatic acute phase response. Hugh increases were detected in the amounts of strongly AAL-reactive fractions of AGP, presumably containing three or more fucosylated N-acetyllactosamine units. At least part of these Lewis X-type glycans (Gal beta 1-->[Fuc alpha 1-->3]GlcNAc-R) appeared to be substituted also with an alpha 2-->3-linked sialic acid residue. This was revealed by the laparotomy-induced abundant staining of AGP with an antisialyl Lewis X monoclonal antibody (CSLEX-1) on blots of sodium dodecyl sulfate-polyacrylamide gels containing AGP isolated from the sera of a patient at various days after operation. It is concluded that acute inflammation induces a strong increase in sialyl Lewis X-substituted AGP molecules that persists at a high level throughout the inflammatory period. We postulate that these changes represent a physiological feedback response on the interaction between leukocytes and inflamed endothelium, which is mediated via sialylated Lewis X structures and the selectin endothelial-leukocyte adhesion molecule 1.

PMID: 7679706