Functions as transport protein in the blood stream. Binds various ligands in the interior of its beta-barrel domain. Also binds synthetic drugs and influences their distribution and availability in the body. Appears to function in modulating the activity of the immune system during the acute-phase reaction. Expressed by the liver and secreted in plasma. Synthesis is controlled by glucocorticoids, interleukin-1 and interleukin-6, It increases 5- to 50-fold upon inflammation. Contains a beta-barrel that binds various ligands in its interior. N-glycosylated. N-glycan heterogeneity at Asn-33: Hex5HexNAc4 (minor), Hex6HexNAc5 (major) and dHex1Hex6HexNAc5 (minor). Three common alleles of ORM1 are known. ORM1*F1 has Gln-38/Val-174; ORM1*F2 has Gln-38/Met-174 and ORM1*S has Arg-38/Val-174. The sequence shown is that of allele ORM1*S. Belongs to the calycin superfamily. Lipocalin family.