One way is to do the lysis in something like plain PBS buffer, and do a high speed spin. Then you can resuspend the pellet in 0.25M sucrose plus tris. Then layer the rsuspension on a sucrose gradient, 28-35% ( add 28g of sucrose and bring up to 100g with buffer, I.e for 28%). Then spin 100,000 xg. Collect the layer that has your protein. Determine a detergent that will dissolve the membranes. Then do electrophoresis. Or put the membranes directly into loading buffer and do the electrophoresis. I am assuming you mean SDS PAGE.