A nonionic detergent used to solubilize membrane proteins; CMC = 4.88 mM under no salt conditions, which decreases in the presence of sodium chloride; has been used to reconstitute amino acid transporters from rat liver plasma membrane vesicles into artificial phospholipid membranes; has also been used to solubilize the melibiose transport carrier from E. coli membranes and reconstitute it into liposomes