Scavenger receptor class B member 1 (SRB1) also known as SR-BI is a protein that in humans is encoded by the SCARB1 gene.

The protein encoded by this gene is a plasma membrane receptor for high density lipoprotein cholesterol (HDL). The encoded protein mediates cholesterol transfer to and from HDL. In addition, this protein is a receptor for hepatitis C virus glycoprotein E2. Two transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Mar 2011].
Function: Receptor for different ligands such as phospholipids, cholesterol ester, lipoproteins, phosphatidylserine and apoptotic cells. Probable receptor for HDL, located in particular region of the plasma membrane, called caveolae. Facilitates the flux of free and esterified cholesterol between the cell surface and extracellular donors and acceptors, such as HDL and to a lesser extent, apoB-containing lipoproteins and modified lipoproteins. Probably involved in the phagocytosis of apoptotic cells, via its phosphatidylserine binding activity. Receptor for hepatitis C virus glycoprotein E2. Binding between SCARB1 and E2 was found to be independent of the genotype of the viral isolate. Plays an important role in the uptake of HDL cholesteryl ester (By similarity).