The slurry was then homogenized
in a Potter-Elvehjem homogenizer with a tight-fitting pestle. The homogenate
was centrifuged twice at 10,000 g for 10 min. The postmitochondrial
supernatant was centrifuged 60 min at 100,000 g. The microsomal
pellets were surface washed with SI buffer (25 mM sucrose and
25 mM imidazole, pH 7.2 [SI]) and stored frozen in liquid N2. The
supernatant (liver cytosol) was stored frozen at -20°C. Rat liver microsomes
and cytosol were prepared as described by Suttie et al. (9).