Correction to �Different structural states of the proteolipid membrane are produced by ligand binding to the human d-opioid receptor as shown by plasmon-waveguide resonance spectroscopy� In this article [Alves ID, Cowell SM, Salamon Z, Devanathan S, Tollin G, and Hruby VJ (2004) Mol Pharmacol 65:1248-1257], a ratio was reported incorrectly. On page 1250, beginning on the last line of the left column and continuing into the right column, the ratio of squalene/butanol/methanol should read �(0.05:9.5:0.5, v/v/v)�. The online version will be corrected in departure from print. The authors regret this error and apologize for any confusion or inconvenience it may have caused.