Orosomucoid (ORM) or alpha-1-acid glycoprotein (''α₁AGp'', ''AGP'' or ''AAG'') is an

acute phase protein Acute-phase proteins (APPs) are a class of proteins whose concentrations in blood plasma either increase (positive acute-phase proteins) or decrease (negative acute-phase proteins) in response to inflammation. This response is called the ''acute-p ...

found in

plasma Plasma or plasm may refer to: Science * Plasma (physics), one of the four fundamental states of matter * Plasma (mineral), a green translucent silica mineral * Quark–gluon plasma, a state of matter in quantum chromodynamics Biology * Blood pla ...

. It is an

alpha-globulin Alpha globulins are a group of globular proteins in blood plasma, plasma that are highly mobile in alkaline or electrically charged solutions. They inhibit certain blood proteases and show significant inhibitor activity. The alpha globulins typic ...

glycoprotein Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycos ...

and is modulated by two polymorphic genes. It is synthesized primarily in hepatocytes and has a normal plasma concentration between 0.6–1.2 mg/mL (1–3% plasma protein). Plasma levels are affected by pregnancy, burns, certain drugs, and certain diseases, particularly HIV. The only established function of ORM is to act as a carrier of basic and neutrally charged lipophilic compounds. In medicine, it is known as the primary carrier of basic (negatively charged) drugs (whereas albumin carries acidic (positively charged) and neutral drugs),

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

s, and protease inhibitors. Aging causes a small decrease in plasma albumin levels; if anything, there is a small increase in alpha-1-acid glycoprotein. The effect of these changes on drug protein binding and drug delivery, however, appear to be minimal. AGP shows a complex interaction with thyroid homeostasis: AGP in low concentrations was observed to stimulate the thyrotropin (TSH) receptor and intracellular accumulation of cyclic AMP. High AGP concentrations, however, inhibited TSH signalling. Alpha-1-acid glycoprotein has been identified as one of four potentially useful circulating biomarkers for estimating the five-year risk of all-cause mortality (the other three are albumin, very low-density lipoprotein particle size, and citrate). Orosomucoid increases in amount in obstructive

jaundice Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...

s while diminishes in hepatocellular jaundice and in intestinal infections.

References

External links

* Acute-phase proteins Glycoproteins Molecular biology Proteomics {{gene-9-stub