Biochemical characterization of the interaction between XXXX and phospholipids.

@entity2285 @entity1878 @entity460 @entity972 @entity4334
UNASSIGNED: Seventy-kilodalton heat shock proteins ( @entity2285 s) are molecular chaperones essential for maintaining cellular homeostasis. Apart from their indispensable roles in protein homeostasis, specific @entity2285 s localize at the plasma membrane and bind to specific lipids. The interaction of @entity2285 s with lipids has direct physiological outcomes including lysosomal rescue, microautophagy, and promotion of cell apoptosis. Despite these essential functions, the @entity2285 -lipid interactions remain largely uncharacterized. In this study, we characterized the interaction of @entity1878 , an inducible @entity2285 , with five phospholipids. We first used high concentrations of @entity972 and established that @entity1878 embeds in membranes when bound to all anionic lipids tested. Furthermore, we found that protein insertion is enhanced by increasing the saturation level of the lipids. Next, we determined that the @entity4334 -binding domain (NBD) of the protein binds to lipids quantitatively more than the substrate-binding domain (SBD). However, for all lipids tested, the full-length protein is necessary for embedding. We also used @entity460 and reaction buffers equilibrated at different pH values and determined that electrostatic interactions alone may not fully explain the association of @entity1878 with lipids. We then determined that lipid binding is inhibited by @entity4334 -binding, but it is unaffected by protein-substrate binding. These results suggest that the @entity1878 lipid-association is specific, depends on the physicochemical properties of the lipid, and is mediated by multiple molecular forces. These mechanistic details of the @entity2285 -lipid interactions establish a framework of possible physiological functions as they relate to chaperone regulation and localization.
