Functions as a 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. {ECO:0000269|PubMed:17008009, ECO:0000269|PubMed:17321687}. This is the function of Ensembl gene identifier ENSG00000229314 (ORM1, orosomucoid 1).