Researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) have found new evidence to explain how cholesteryl ester transfer protein (CETP) mediates the transfer of cholesterol from ‘good’ high density lipoproteins (HDLs) to ‘bad’ low density lipoproteins (LDLs). These findings point the way to the design of safer, more effective next generation CETP inhibitors that could help prevent the development of heart disease. Gang Ren, a materials physicist and electron microscopy expert with Berkeley Lab’s Molecular Foundry, led a study in which the first structural images of CETP interacting with HDLs and LDLs were recorded. The images and structural analyses support the hypothesis that cholesterol is transferred from HDLs to LDLs via a tunnel running through the center of the CETP molecule.