Western blots.

Western analysis of apolipoproteins, lipoproteins, and proteins involved in lipoprotein metabolism can be challenging due to their size, hydrophobic nature, and, in some cases, low abundance. Here we describe a Western blotting method that has been used successfully for many proteins involved in lipoprotein metabolism, as well as intact LDL or HDL particles. Proteins or lipoprotein particles separated by gel electrophoresis are transferred to a PVDF membrane in a Hoefer TE22 transfer tank with Tris-Glycine-SDS-Methanol transfer buffer. The membrane is blocked with 3 % BSA/5 % milk to prevent nonspecific binding of antibody to the membrane and is then incubated with primary antibody that binds specifically to the protein of interest. After washing away unbound primary antibody, the membrane is then incubated with an HRP-labeled secondary antibody that binds primary antibody. After washing away unbound secondary antibody, the membrane is then incubated with a substrate for HRP, generating a chemiluminescent signal at the location of the protein of interest. The protein is visualized by exposing the membrane to an autoradiography film or an imaging device. Information on the use of several human antibodies, including apoA-I, A-II, apoB, apoC-II, apoC-III, apoD, apoL1, apoM, PON1, SAA, ABCA1, nitrotyrosine, and LCAT, is provided. This method can be used for Western blotting of virtually any protein as well as native lipoprotein particles.