Figure 6.

Lipid raft analysis of scavenger receptor class B type I (SR-BI). Sucrose gradient centrifugation of Mg²⁺ precipitated (A) and microvillar (B) membranes prepared from the same mucosal homogenate. The membranes were prepared, extracted with 1% ice cold Triton X-100, and subjected to sucrose gradient centrifugation, as described in the methods section. Samples of the gradient fractions were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoblotting for the distribution of SR-BI and, in the case of the microvillar gradient, for the lipid raft marker galectin-4 (Gal-4) and the “non-raft” marker lactase-phlorizin hydrolase. Gradient fractions containing lipid raft membranes and soluble (“non-raft”) proteins are indicated by arrows.