IDENTIFICATION OF SCAVENGER RECEPTOR SR-BI AS A HIGH-DENSITY-LIPOPROTEIN RECEPTOR

High density lipoprotein (HDL) and low density lipoprotein (LDL) are c holesterol transport particles whose plasma concentrations are directl y (LDL) and inversely (HDL) correlated with risk for atherosclerosis. LDL catabolism involves cellular uptake and degradation of the entire particle by a well-characterized receptor. HDL, in contrast, selective ly delivers its cholesterol, but not protein, to cells by unknown rece ptors. Here it is shown that the class B scavenger receptor SR-BI is a n HDL receptor. SR-BI binds HDL with high affinity, is expressed prima rily in liver and nonplacental steroidogenic tissues, and mediates sel ective cholesterol uptake by a mechanism distinct from the classic LDL receptor pathway.