Solubilization of P100 membrane fractions. Total lysate (Tot. Lys.) was separated into S100 and P100 fractions at 100,000 rcf for 1 h. P100 membranes were solubilized in 1% (w/v) detergent for 1 h and then separated into P100(sol) and P100(n/sol) fractions at 100,000 rcf for 1 h. Samples were separated by SDS–PAGE and analyzed by immunoblotting with α-polyhistidine-HRP. n-octyl β-d-glucopyranoside (OTG), Triton X-100 (Triton), 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), and n-dodecyl β-d-maltopyranoside (DDM). Blot representative of three separate experiments.