(scavenger receptor class B member 1, SCARB1) belongs to the CD36
family and acts as a cell surface lipoprotein receptor for a variety of ligands including high density lipoprotein
(HDL), phospholipids, phosphatidylserine, and lipoproteins such as lipopolysaccharide (LPS). SR-BI mediates selective uptake of HDL cholesteryl (HDL-C) ester in the liver, steroidogenic tissues, and adipose tissue and facilitates the flux of free and esterified cholesterol between the cell surface and apoB
-containing lipoproteins and modified lipoproteins. SR-BI plays a role in antigen capture and cross-presentation from bacteria
, parasites, and viruses
such as Hepatitis C
. In endothelial cells
and macrophages, SR-BI is involved in anti-inflammatory and pro-survival signaling, providing protection against atherosclerosis and clearing apoptotic
cells (efferocytosis) (1, 2).
At least 5 different human splice variants have been identified with theoretical molecular weights ranging from 60.9 kDa for the canonical sequence to 45 kDa for an N-terminally truncated variant (SR-BII
) (3). The extracellular domain of human SR-BI (CLA-1) shares 80%, 80%, 89%, 86% and 84% aa sequence identity with mouse, rat, porcine, rabbit, and bovine SR-BI, respectively. SR-BI is highly glycosylated and removal of N-linked glycosylation reduces lipid transport.
1. Linton MF, Tao H, Linton EF, Yancey PG. (2017) SR-BI: A Multifunctional Receptor in Cholesterol Homeostasis and Atherosclerosis. Trends Endocrinol Metab. 28(6):461-472. PMID: 28259375
2. Hoekstra M, Sorci-Thomas M. (2017) Rediscovering scavenger receptor type BI: surprising new roles for the HDL receptor. Curr Opin Lipidol. 28(3):255-260. PMID: 28301373
3. Shen WJ, Asthana S, Kraemer FB, Azhar S. (2018) Scavenger receptor B type 1: expression, molecular regulation, and cholesterol transport function.