Figure 1.

Protein content of plasma membrane DRMs from MDCK cells. Surface biotinylated MDCK cells were extracted with 1% Tween 20, 1% Brij 58, 0.5% Lubrol WX, 1% Brij 98, 0.5% Brij 96, and 1% Triton or 4% CHAPS. DRMs were prepared by flotation on sucrose step gradients. Equivalent aliquots of the starting material before detergent treatment, which contained the total plasma membrane protein (PM), and the various DRMs were analyzed by Western blotting using peroxidase-conjugated extravidin to reveal biotinylated proteins. Two exposures of the same membrane are shown. The amounts of biotinylated protein were quantified, setting PM to 100%.