N-Octyl-β-D-thioglucopyranoside (octylthioglucoside, OTG) is a mild nonionic detergent characterized by a thioglycosidic linkage that is used for effective cell lysis or to solubilise integral membrane proteins without denaturing their tertiary or quaternary structure; this property is particularly of use in order to crystallise them for structural studies or to reconstitute them into artificial lipid bilayers for functional assays.