Fig. 3. Isolation and characterization of low density detergent-insoluble membrane (LD-DIM) fraction from Xenopus unfertilized eggs. (A) Schematic diagram for preparation of LD-DIM fraction from Xenopus eggs. (B) Egg LD-DIM fraction, a light-scattering band, is indicated by an asterisk. (C) Protein silver staining of sucrose density gradient fractions. Proteins (20 µl of each fraction) were separated by SDS-PAGE on a 12.5% gel. Prestained molecular size markers are as in Fig. 1 plus ß-lactoglobulin A (25.5 kDa) and lysozyme (16.5 kDa). Each sucrose density gradient fraction was assayed for the content of (D) protein, (E) cholesterol and (F) GM1-ganglioside. (G) Fractions were separated by SDS-PAGE on 8%, 12.5% or 16% gels, and analyzed by immunoblotting with the indicated specific antibodies. An asterisk indicates the position of Xyk in the LD-DIM fractions.