ORM1 Human

ORM1 is an alpha-globulin glycoprotein with a molecular weight of approximately 40,000 Da . It consists of a single polypeptide chain of about 180 amino acids . The protein is synthesized mainly in hepatocytes, but it is also expressed in other tissues such as the brain and adipose tissue . ORM1 has a normal plasma concentration ranging between 0.6–1.2 mg/mL, accounting for 1–3% of plasma proteins .

The primary function of ORM1 is to act as a transport protein in the bloodstream. It binds various ligands within its beta-barrel domain, including synthetic drugs, and influences their distribution and availability in the body . ORM1 also plays a role in modulating the immune system’s activity during the acute-phase reaction .

ORM1 is classified as an acute-phase reactant, meaning its plasma levels increase significantly during acute infections and inflammation . This makes it a useful biomarker for various inflammatory conditions. Plasma levels of ORM1 can be affected by factors such as pregnancy, burns, certain drugs, and diseases like HIV . Additionally, ORM1 has been identified as one of four circulating biomarkers potentially useful for estimating the five-year risk of all-cause mortality .

The ORM1 gene is located on chromosome 9 (q31-qter) and is modulated by two polymorphic genes . An important paralog of this gene is ORM2 . Variants in the ORM1 gene can affect the protein’s plasma concentration and its interaction with drugs and other ligands .

Research into ORM1 continues to uncover its complex interactions with various physiological processes. For instance, ORM1 has been observed to interact with thyroid homeostasis, stimulating the thyrotropin (TSH) receptor at low concentrations and inhibiting TSH signaling at high concentrations . This highlights its potential role in endocrine regulation.