Sterol carrier protein (SCP), also known as liver fatty acid binding protein, is a major adrenal protein localized in the cytosol and inner mitochondrial membrane. SCP is synthesized in liver and intestine and then rapidly secreted into blood, where it associates primarily with the high density lipoprotein fraction. Studies using steroidogenesis inhibitors showed that corticotropin has a specific effect on the uptake of SCP and its movement with cholesterol to the inner mitochondrial membrane. Thus, SCP appears to be intimately involved in the mechanism(s) of adrenal steroidogenesis from cholesterol.