Our lab is investigating a unique function of ABCA1 (and additionally ABCG1 in the mouse) that mediates macrophage deposition of unesterified cholesterol into the extracellular matrix.  The extracellular cholesterol deposits can be mobilized by agents such as HDL, ApoA-I, and ApoA-I mimetic peptides, mobilization by the latter two entities requiring ABCA1’s other known function to complex phospholipid with amphipathic apolipoproteins.  Surprisingly, the deposited cholesterol is not contained within vesicles or membranous structures, but rather within branching amorphous material whose composition is under investigation, as is the trafficking of cellular cholesterol that leads to these extracellular cholesterol deposits.