SOAT2
Domain
Each protomer consists of 9 transmembrane segments, which enclose a cytosolic tunnel and a transmembrane tunnel that converge at the predicted catalytic site: acyl-CoA enters the active site through the cytosolic tunnel, whereas cholesterol enters from the side through the transmembrane tunnel.
Function
Catalyzes the formation of fatty acid-cholesterol esters, which are less soluble in membranes than cholesterol (PubMed:11294643, PubMed:16647063). Plays a role in lipoprotein assembly and dietary cholesterol absorption (PubMed:11294643). Utilizes oleoyl-CoA ((9Z)-octadecenoyl-CoA) and linolenoyl-CoA ((9Z,12Z,15Z)-octadecatrienoyl-CoA) as substrates (PubMed:11294643). May provide cholesteryl esters for lipoprotein secretion from hepatocytes and intestinal mucosa (PubMed:11294643).
Isoform 2
Has lower enzymatic activity compared to isoform 1.
Isoform 3
Has lower enzymatic activity compared to isoform 1.
Post-translational modifications
Polyubiquitinated by AMFR/gp78 at Cys-277, leading to its degradation when the lipid levels are low (PubMed:28604676). Association with AMFR/gp78 is mediated via interaction with INSIG1 (PubMed:28604676). High concentration of cholesterol and fatty acid results in Cys-277 oxidation, preventing ubiquitination at the same site, resulting in protein stabilization (PubMed:28604676).
Oxidized at Cys-277: high concentration of cholesterol and fatty acid induce reactive oxygen species, which oxidizes Cys-277, preventing ubiquitination at the same site, and resulting in protein stabilization.
Sequence Similarities
Belongs to the membrane-bound acyltransferase family. Sterol o-acyltransferase subfamily.
Tissue Specificity
Expression seems confined in hepatocytes and enterocytes.
Cellular localization
- Endoplasmic reticulum membrane
- Multi-pass membrane protein
Alternative names
ACACT2, ACAT2, SOAT2, Sterol O-acyltransferase 2, Acyl-coenzyme A:cholesterol acyltransferase 2, Cholesterol acyltransferase 2, ACAT-2