TY - JOUR
T1 - Functional characterization of human 1-acylglycerol-3-phosphate acyltransferase isoform 8
T2 - Cloning, tissue distribution, gene structure, and enzymatic activity
AU - Agarwal, Anil K.
AU - Barnes, Robert I.
AU - Garg, Abhimanyu
N1 - Funding Information:
We thank Ruth Giselle Huet, Keliang Xu, Vidya Rai, Katie Tunison, and Danika Taylor for technical assistance, Beverley Adams-Huet for statistical analysis and Richard Auchus, MD. Ph.D. and Ken Chamberliss, Ph.D. for critical review of the manuscript. This work was supported by the National Institutes of Health Grants R01-DK54387 and by the Southwestern Medical Foundation.
PY - 2006/5/15
Y1 - 2006/5/15
N2 - Glycerophospholipids and triglycerides are synthesized de novo by cells through an evolutionary conserved process involving serial acylations of phosphorylated glycerol. Various isoforms of the enzyme, 1-acylglycerol-3-phosphate acyltransferase (AGPAT), acylate lysophosphatidic acid at the sn-2 position to produce phosphatidic acid. We cloned a cDNA predicted to be AGPAT isoform and designated it AGPAT8. Human and mouse AGPAT8 proteins are 89% homologous, and their gene structure is also highly conserved. AGPAT8 is most closely related to AGPAT5, and its cDNA is expressed most in the heart, while AGPAT5 is expressed more in the prostate and testis. In cell lysates, AGPAT8 shows moderate acyltransferase activity with [3H]oleoyl-CoA but lacks acyl-CoA:lysocardiolipin acyltransferase activity. In whole cells upon incubation with [14C]linoleic acid, most of the radioactivity was recovered in phosphatidyl ethanolamine, phosphatidyl choline and phosphatidic acid fraction. Of the two well conserved acyltransferase motifs, NHX4D is present in AGPAT8, whereas arginine in the EGTR motif is substituted by aspartate. However, mutation of EGTD to EGTR did not increase enzymatic activity significantly. Based on the X-ray crystallographic structure of a related acyltransferase, squash gpat, a model is proposed in which a hydrophobic pocket in AGPAT8 accommodates fatty acyl chains of both substrates in an orientation where the NHX4D motif participates in catalysis.
AB - Glycerophospholipids and triglycerides are synthesized de novo by cells through an evolutionary conserved process involving serial acylations of phosphorylated glycerol. Various isoforms of the enzyme, 1-acylglycerol-3-phosphate acyltransferase (AGPAT), acylate lysophosphatidic acid at the sn-2 position to produce phosphatidic acid. We cloned a cDNA predicted to be AGPAT isoform and designated it AGPAT8. Human and mouse AGPAT8 proteins are 89% homologous, and their gene structure is also highly conserved. AGPAT8 is most closely related to AGPAT5, and its cDNA is expressed most in the heart, while AGPAT5 is expressed more in the prostate and testis. In cell lysates, AGPAT8 shows moderate acyltransferase activity with [3H]oleoyl-CoA but lacks acyl-CoA:lysocardiolipin acyltransferase activity. In whole cells upon incubation with [14C]linoleic acid, most of the radioactivity was recovered in phosphatidyl ethanolamine, phosphatidyl choline and phosphatidic acid fraction. Of the two well conserved acyltransferase motifs, NHX4D is present in AGPAT8, whereas arginine in the EGTR motif is substituted by aspartate. However, mutation of EGTD to EGTR did not increase enzymatic activity significantly. Based on the X-ray crystallographic structure of a related acyltransferase, squash gpat, a model is proposed in which a hydrophobic pocket in AGPAT8 accommodates fatty acyl chains of both substrates in an orientation where the NHX4D motif participates in catalysis.
KW - Acyltransferase
KW - Lipodystrophy
KW - Phospholipids
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U2 - 10.1016/j.abb.2006.03.014
DO - 10.1016/j.abb.2006.03.014
M3 - Article
C2 - 16620771
AN - SCOPUS:33646145315
SN - 0003-9861
VL - 449
SP - 64
EP - 76
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 1-2
ER -