Lipid-binding Proteins in Membrane Digestion, Antigen Presentation, and Antimicrobial Defense

Membrane-active proteins are able to bind lipid molecules, transfer lipids to proteins or to target membranes, and selectively perturb lipid bilayers (1). They differ in binding specificity and subcellular localization and also in their cytoplasmic, extracytoplasmic, and intercellular topology and functions. Lipid-binding proteins include, for example, cholesterol-binding proteins, like NPC-1 and -2 or ABCA1 (1). A subset of lipid-binding proteins has a major role in the lysosomal degradation of sphingolipids with short hydrophilic head groups.