Subcellular localization and regulation of StarD4 protein in macrophages and fibroblasts

► StarD4 is a START domain protein with a cholesterol-specific lipid binding pocket. ► StarD4 is found in hepatocytes, macrophages and fibroblast in the cytoplasm and ER. ► StarD4 is regulated by sterols and upregulated during macrophage differentiation. ► The protein is able to increase ACAT activity in an in vitro assay. ► StarD4 is a highly regulated, non-vesicular, directional cholesterol transporter.