ApoB is large protein, ~550KDa. I searched the literature and most of the published articles brifely described the prosedure of IP. They added SDS in lysis buffer and lyzed the cells overnight to dissolve ApoB. I followed these key points but got poor IP of ApoB. After centrifugation of the cell lysis, the supernatant was cloudy and I found ApoB existed in the undissolved part in the supernatant. Dose anyone have an idea to increase the solubility of large protein in cell lysis? Dose ultrasonication work?