Horizontal semi-dry electroblotting for the detection of the low density lipoprotein receptor in solubilized liver membranes

A high efficiency transfer of the low density lipoprotein (LDL) receptor proteins from polyacrylamide slab gel onto immobilizing nitrocellulose membranes using the horizontal semi‐dry electrophoretic system is described. The transfer of the LDL receptors from solubilized rat liver microsomes was performed between two graphite plate electrodes in a continuous buffer system containing methanol and sodium dodecyl sulfate. The protein transfer was achieved in only 150 min at a constant current of 0.8 mA/cm2 at room temperature with very low Joule heat development. The homogeneous electric field yield between the two electrode plates produced a satisfactory transfer of the LDL‐receptor protein band in spite of its high molecular weight, and only few protein traces remained in the polyacrylamide gel after blotting. This improved method allows a rapid and quantitative transfer of the LDL receptors without protein denaturation, since the specific binding activity of the blotted receptor is retained as demonstrated by ligand‐blotting and immuno‐blotting.