Equilibrium partitioning of an intracellular bile acid binding protein in the presence of phospholipid vesicles

Bile acid binding proteins are a class of cytosolic proteins known to participate in lipid transport and homeostasis1. These relatively small biomolecules are responsible for the translocation of hydrophobic or amphiphilic molecules across the cell, delivering their cargo to the cell membrane or to other cellular components. In the present work we address the mechanisms of lipid transfer from and to the membranes, with the aim of characterizing the binding equilibria describing the partitioning of these proteins between free and membrane-bound states. As a development of a previous work2, charged and neutral liposomes (LUVs and SUVs) are here employed in the solution NMR interaction studies with liver-bile acid binding protein.