A precast gel and blotting membrane combination unit and method of use. The device includes two plates, each plate having a conductive opaque region with conductive polymers and a transparent region having static-dissipative polymers. Between the plates are a gel matrix and blotting membrane. The device is placed in a tank capable of both performing the electrophoresis phase and transfer phase of a western blot. During the electrophoresis phase, current flows from a pair of electrophoresis electrodes to separate proteins by size. The user can visualize the extent of protein separation by observing a tracking dye through the transparent region. After the electrophoresis phase, voltage is switched to a pair of transfer phase electrodes. The device allows current to flow through the conductive opaque regions of the plates to transfer separated proteins to a blotting membrane directly after electrophoresis without having to remove or reorient the device in the tank.