Catalytic properties of MGAT3, a putative triacylgycerol synthases⃞
Acyl-coenzyme A:monoacylglycerol acyltransferase 3 (MGAT3) is a member of the MGAT family of enzymes that catalyze the synthesis of diacylglycerol (DAG) from monoacylglycerol (MAG), a committed step in dietary fat absorption. Although named after the initial identification of its MGAT activity, MGAT...
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| Format: | Article |
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Elsevier
2007-03-01
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| Series: | Journal of Lipid Research |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S002222752043233X |
| _version_ | 1818640010445848576 |
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| author | Jingsong Cao Long Cheng Yuguang Shi |
| author_facet | Jingsong Cao Long Cheng Yuguang Shi |
| author_sort | Jingsong Cao |
| collection | DOAJ |
| description | Acyl-coenzyme A:monoacylglycerol acyltransferase 3 (MGAT3) is a member of the MGAT family of enzymes that catalyze the synthesis of diacylglycerol (DAG) from monoacylglycerol (MAG), a committed step in dietary fat absorption. Although named after the initial identification of its MGAT activity, MGAT3 shares higher sequence homology with acyl-coenzyme A:diacylglycerol acyltransferase 2 (DGAT2) than with other MGAT enzymes, suggesting that MGAT3 may also possess significant DGAT activity. This study compared the catalytic properties of MGAT3 with those of MGAT1 and MGAT2 enzymes using both MAG and DAG as substrates. Our results showed that in addition to the expected MGAT activity, the recombinant MGAT3 enzyme expressed in Sf-9 insect cells displayed a strong DGAT activity relative to that of MGAT1 and MGAT2 enzymes in the order MGAT3 > MGAT1 > MGAT2. In contrast, none of the three MGAT enzymes recognized biotinylated acyl-CoA or MAG as a substrate. Although MGAT3 possesses full DGAT activity, it differs from DGAT1 in catalytic properties and subcellular localization. The MGAT3 activity was sensitive to inhibition by the presence of 1% CHAPS, whereas DGAT1 activity was stimulated by the detergent. Consistent with high sequence homology with DGAT2, the MGAT3 enzyme demonstrated a similar subcellular distribution pattern to that of DGAT2, but not DGAT1, when expressed in COS-7 cells. Our data suggest that MGAT3 functions as a novel triacylglycerol (TAG) synthase that catalyzes efficiently the two consecutive acylation steps in TAG synthesis. |
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| id | doaj.art-a399f16120064d5f99540d48f305e8c2 |
| institution | Directory Open Access Journal |
| issn | 0022-2275 |
| language | English |
| last_indexed | 2024-12-16T23:04:28Z |
| publishDate | 2007-03-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Lipid Research |
| spelling | doaj.art-a399f16120064d5f99540d48f305e8c22022-12-21T22:12:36ZengElsevierJournal of Lipid Research0022-22752007-03-01483583591Catalytic properties of MGAT3, a putative triacylgycerol synthases⃞Jingsong Cao0Long Cheng1Yuguang Shi2Endocrine Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285Department of Cellular and Molecular Physiology, Pennsylvania State University School of Medicine, Hershey, PA 17033Endocrine Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285; Department of Cellular and Molecular Physiology, Pennsylvania State University School of Medicine, Hershey, PA 17033Acyl-coenzyme A:monoacylglycerol acyltransferase 3 (MGAT3) is a member of the MGAT family of enzymes that catalyze the synthesis of diacylglycerol (DAG) from monoacylglycerol (MAG), a committed step in dietary fat absorption. Although named after the initial identification of its MGAT activity, MGAT3 shares higher sequence homology with acyl-coenzyme A:diacylglycerol acyltransferase 2 (DGAT2) than with other MGAT enzymes, suggesting that MGAT3 may also possess significant DGAT activity. This study compared the catalytic properties of MGAT3 with those of MGAT1 and MGAT2 enzymes using both MAG and DAG as substrates. Our results showed that in addition to the expected MGAT activity, the recombinant MGAT3 enzyme expressed in Sf-9 insect cells displayed a strong DGAT activity relative to that of MGAT1 and MGAT2 enzymes in the order MGAT3 > MGAT1 > MGAT2. In contrast, none of the three MGAT enzymes recognized biotinylated acyl-CoA or MAG as a substrate. Although MGAT3 possesses full DGAT activity, it differs from DGAT1 in catalytic properties and subcellular localization. The MGAT3 activity was sensitive to inhibition by the presence of 1% CHAPS, whereas DGAT1 activity was stimulated by the detergent. Consistent with high sequence homology with DGAT2, the MGAT3 enzyme demonstrated a similar subcellular distribution pattern to that of DGAT2, but not DGAT1, when expressed in COS-7 cells. Our data suggest that MGAT3 functions as a novel triacylglycerol (TAG) synthase that catalyzes efficiently the two consecutive acylation steps in TAG synthesis.http://www.sciencedirect.com/science/article/pii/S002222752043233Xacyl-coenzyme A:monoacylglycerol acyltransferaseacyltransferasemonoacylglycerol |
| spellingShingle | Jingsong Cao Long Cheng Yuguang Shi Catalytic properties of MGAT3, a putative triacylgycerol synthases⃞ Journal of Lipid Research acyl-coenzyme A:monoacylglycerol acyltransferase acyltransferase monoacylglycerol |
| title | Catalytic properties of MGAT3, a putative triacylgycerol synthases⃞ |
| title_full | Catalytic properties of MGAT3, a putative triacylgycerol synthases⃞ |
| title_fullStr | Catalytic properties of MGAT3, a putative triacylgycerol synthases⃞ |
| title_full_unstemmed | Catalytic properties of MGAT3, a putative triacylgycerol synthases⃞ |
| title_short | Catalytic properties of MGAT3, a putative triacylgycerol synthases⃞ |
| title_sort | catalytic properties of mgat3 a putative triacylgycerol synthases⃞ |
| topic | acyl-coenzyme A:monoacylglycerol acyltransferase acyltransferase monoacylglycerol |
| url | http://www.sciencedirect.com/science/article/pii/S002222752043233X |
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