Phenol-acetic acid-urea polyacrylamide gel electrophoresis of membrane proteins.

A phenol-acetic acid-urea polyacrylamide gel electrophoretic system (PAU-PAGE) was simplified by adaptation to a slab gel format, allowing the simultaneous comparison of up to 12 samples. The system fractionated most proteins according to molecular mass, although chemical reduction was required since certain proteins (e.g., bovine serum albumin) showed reduction-dependent shifts in mobility. Sodium dodecyl sulfate-PAGE of partially purified membrane proteins can be adversely affected by protein aggregation and proteolysis. PAU-PAGE, which solubilized aqueous insoluble proteins and rapidly inactivated proteases, was useful for assessing the polypeptide composition of plasma membrane preparations.