Coating cells with cationic silica-magnetite nanocomposites for rapid purification of integral plasma membrane proteins.

This study developed a simple and rapid purification method for plasma membrane with high yields from adherent cells. The plasma membrane (PM) sheets could be absorbed specifically by the cationic silica-magnetite nanocomposites (CSMN) under acidic conditions, and recovered directly in cell-lysis-buffer with no need for precipitation. The binding between CSMN and PM sheets was confirmed by electron microscopy. Western blot analysis demonstrated a >10-fold relative enrichment factor. Up to 422 integral membrane proteins were identified from 10(7) Huh7 cells. Notably, we found 29 Ras family proteins by classification according to their biological functions. The whole enrichment procedure took <30 min. The CSMN-based procedure demonstrates a simple, economical and efficient enrichment of integral PM proteins in proteomic study.