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Biochim Biophys Acta. 2014 Sep;1841(9):1318-28. doi: 10.1016/j.bbalip.2014.06.004. Epub 2014 Jun 19.

Characterization of the interaction of diacylglycerol acyltransferase-2 with the endoplasmic reticulum and lipid droplets.

Author information

1
Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
2
Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada.
3
Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
4
Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada. Electronic address: scot.stone@usask.ca.

Abstract

Acyl CoA:diacylglycerol acyltransferase-2 (DGAT2) is an integral membrane protein that catalyzes the synthesis of triacylglycerol (TG). DGAT2 is present in the endoplasmic reticulum (ER) and also localizes to lipid droplets when cells are stimulated with oleate. Previous studies have shown that DGAT2 can interact with membranes and lipid droplets independently of its two transmembrane domains, suggesting the presence of an additional membrane binding domain. In order to identify additional membrane binding regions, we confirmed that DGAT2 has only two transmembrane domains and demonstrated that the loop connecting them is present in the ER lumen. Increasing the length of this short loop from 5 to 27 amino acids impaired the ability of DGAT2 to localize to lipid droplets. Using a mutagenesis approach, we were able to identify a stretch of amino acids that appears to have a role in binding DGAT2 to the ER membrane. Our results confirm that murine DGAT2 has only two transmembrane domains but also can interact with membranes via a previously unidentified helical domain containing its active site.

KEYWORDS:

Cysteine; Diacylglycerol acyltransferase; Endoplasmic reticulum; Lipid droplet; Topology; Triacylglycerol

PMID:
24953780
DOI:
10.1016/j.bbalip.2014.06.004
[Indexed for MEDLINE]

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