Model of biologically active apolipoprotein E bound to dipalmitoylphosphatidylcholine

Abstract

Apolipoprotein (apo)E plays a critical role in cholesterol transport, through high affinity binding to the low density lipoprotein receptor. This interaction requires apoE to be associated with a lipoprotein particle. To determine the structure of biologically active apoE on a lipoprotein particle, we crystallized dipalmitoylphosphatidylcholine particles containing two apoE molecules and determined the molecular envelope of apoE at 10 Å resolution. On the basis of the molecular envelope and supporting biochemical evidence, we propose amodel in which each apoE molecule is folded into a helical hairpin with the binding region for the low density lipoprotein receptor at its apex. © 2006 by The American Society for Biochemistry and Molecular Biology, Inc.