BMB Reports 2017; 50(7): 367-372
Monoacylglycerol O-acyltransferase 1 (MGAT1) localizes to the ER and lipid droplets promoting triacylglycerol synthesis
Yoo Jeong Lee1 & Jae-woo Kim2,3,4,*
1Division of Metabolic Disease, Center for Biomedical Sciences, National Institutes of Health, Cheongju 28159, 2Department of Biochemistry and Molecular Biology, Integrated Genomic Research Center for Metabolic Regulation, Institute of Genetic Science, Yonsei University College of Medicine, 3Brain Korea 21 PLUS Project for Medical Science, Yonsei University, 4Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul 03722, Korea
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Received: March 6, 2017; Revised: March 16, 2017; Accepted: March 22, 2017; Published online: July 31, 2017.
© Korean Society for Biochemistry and Molecular Biology. All rights reserved.

Monoacylglycerol acyltransferase 1 (MGAT) is a microsomal enzyme that catalyzes the synthesis of diacylglycerol (DAG) and triacylglycerol (TAG). However, the subcellular localization and catalytic function domain of this enzyme is poorly understood. In this report, we identified that murine MGAT1 localizes to the endoplasmic reticulum (ER) under normal conditions, whereas MGAT1 co-localize to the lipid droplets (LD) under conditions of enriching fatty acids, contributing to TAG synthesis and LD expansion. For the enzyme activity, both the N-terminal transmembrane domain and catalytic HPHG motif are required. We also show that the transmembrane domain of MGAT1 consists of two hydrophobic regions in the N-terminus, and the consensus sequence FLXLXXXn, a putative neutral lipid-binding domain, exists in the first transmembrane domain. Finally, MGAT1 interacts with DGAT2, which serves to synergistically increase the TAG biosynthesis and LD expansion, leading to enhancement of lipid accumulation in the liver and fat.
Keywords: DGAT2, Hepatic steatosis, Lipid droplet, MGAT1, Triacylglycerol synthesis

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