Bicinchoninic acid bca assay reagents

β-FNA, [³H]β-FNA, naloxone, and U50,488H, were provided by the National Institute on Drug Abuse (Bethsada, MD). [³⁵S]guanosine 5′-O-[γ-thio]triphosphate] (GTPγS) (1250 Ci/mmol), [15, 16-³H]diprenorphine ([³H]DIP) (36–50 Ci/mmol) were purchased from PerkinElmer Life Sciences (Boston, MA); polyethyleneimine, ampicillin, leupeptin hydrochloride, phenylmethylsulfonyl fluoride (PMSF), GDP and GTPγS were purchased from Sigma-Aldrich (St. Louis, MO). Geneticin (G418) was purchased from Cellgro Mediatech, Inc. (Herndon, VA). Lipofectamine 2000 and BamHI were purchased from Invitrogen (Carlsbad, CA). XhoI and dNTPs were purchased from Promega (Madison, WI). Minimal essential medium (MEM), trypsin and penicillin/streptomycin were purchased from Gibco Life Technologies (Grand Island, NY). Bicinchoninic acid (BCA) assay reagents were purchased from Thermo Fisher Scientific, Inc. (Rockford, IL). The following reagents were purchased from the indicated companies: GF/B glass filters, Brandel, Inc. (Gaithersburg, MD); PFU DNA polymerase, Agilent Technologies (Santa Rosa, CA); EcoRI, Roche (Indianapolis, IN).