Fig. 4.

Absorbed ³H-oleate is in a detergent resistant membrane fraction as shown by an OptiPrep gradient. A. Intestinal sacs were exposed to [³H]oleate and the cytosol fraction prepared from enterocytes isolated from the sacs (Methods). Cytosol (1 mg) was treated with 1% Triton X-100 and placed at the bottom of a centrifuge tube containing an OptiPrep gradient (Methods). The gradient was centrifuged for 20 h and 1 ml fractions collected from the top of the gradient. The dpm were determined in each fraction (filled circles). Glyceryltri- ³H-oleate (open squares) and ³H-oleate (open circles) were separately dissolved in 1% Triton X-100, centrifuged, the gradient resolved, and the [³H]-dpm determined for each fraction. The data are representative of 3 trials. B. Immunoblots (50 (µg prot) of each fraction from the OptiPrep gradient were performed for the indicated proteins as shown to the right of the blots (Caveolin-1, Caveolin-2, and Caveolin-3, IAP, CD36, FATP4, FABP1, and FABP2). E indicates an empty lane.