Interaction of L-alpha-didecanoyl phosphatidylcholine with the AI polypeptide of high density lipoprotein

Cooperative interaction of L-alpha-didecanoyl phosphatidylcholine with the AI polypeptide from human serum high density lipoprotein results in a complex particle containing 2 molecules of AI and 190 molecules of the lipid. Binding occurs two orders of magnitude above the critical micelle concentration of the lipid and requires the simultaneous presence of low levels of single-chain amphiphiles. The present investigation and previous studies from this laboratory suggest that AI contains "pockets" capable of interacting with a fixed hydrophobic volume and that amphiphilic head groups do not affect the binding capacity.