SCARB1

Function

Scavenger receptor class B, type I (SR-BI) is an integral membrane protein found in numerous cell types/tissues, including the liver and adrenal. It is best known for its role in facilitating the uptake of cholesteryl esters from high-density lipoproteins in the liver. This process drives the movement of cholesterol from peripheral tissues towards the liver, where cholesterol can either be secreted via the bile duct or be used to synthesise steroid hormones. This movement of cholesterol is known as reverse cholesterol transport and is a protective mechanism against the development of atherosclerosis, which is the principal cause of heart disease and stroke.

SR-BI is crucial in lipid soluble vitamin uptake.

In melanocytic cells SCARB1 gene expression may be regulated by the MITF.

Species distribution

SR-BI has also been identified in the livers of non-mammalian species (turtle, goldfish, shark, chicken, frog, and skate), suggesting it emerged early in vertebrate evolutionary history. The turtle also seems to upregulate SB-RI during egg development, indicating that cholesterol efflux may be at peak levels during developmental stages.

Clinical significance

SCARB1 is, along with CD81, the receptor for the entry of the Hepatitis C virus in liver cells.

Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles.