sn-Glycerol-3-phosphate (G3P) is a phosphoric ester of glycerol that is a chemical intermediate in glycolysis and lipid metabolism. [1] G3P is an integral part of the glycerophosphate shuttle, in which NADH is oxidized to regenerate NAD+ and reducing equivalents are transferred to the oxidative phosphorylation pathway.[2][3][4][5] G3P is used as a substrate for lipid biosynthesis pathways in synthetic biology, in studies of reactive oxygen species in heart tissue, and to measure phosphatidic acid in cell cultures.[6] [7][8] It plays a vital role in systemic acquired resistance in plant immunity.[9] G3P availability affects insulin production as a substrate for glycerol-3-phosphate phosphatase. [10] Altered levels of G3P have been found in the saliva of Alzheimer’s, frontal lobe dementia, and Lewy body disease patients.[11]

Reference:
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[2]. Cottingham, I.R., and Ragan, C.I. Purification and properties of L-3-glycerophosphate dehydrogenase from pig brain mitochondria. Biochem J. 192(1), 9-18 (1980).
[3]. Shen, W., Wei, Y., Dauk, M., et al. Involvement of a glycerol-3-phosphate dehydrogenase in modulating the NADH/NAD+ ratio provides evidence of a mitochondrial glycerol-3-phosphate shuttle in Arabidopsis. Plant Cell 18(2), 422-441 (2006).
[4]. Yeh, J.I., Chinte, U., and Du, S.J. Structure of glycerol-3-phosphate dehydrogenase, an essential monotopic membrane enzyme involved in respiration and metabolism. Proc. Natl. Acad. Sci. USA 105(9), 3280-3285 (2008).
[5]. Mrácek, T., Drahota, Z., and Houstěk, J. The function and the role of the mitochondrial glycerol-3-phosphate dehydrogenase in mammalian tissues. Biochim Biophys. Acta. 1827(3), 401-410 (2013).
[6]. Scott, A., Noga, M.J., De Graaf, P.T., et al. Cell-free phospholipid biosynthesis by gene-encoded enzymes reconstituted in liposomes. PLoS One 11(10), e0163058 (2016).
[7]. Madungwe, N., Zilberstein, N.F., Feng, Y., et al. Critical role of mitochondrial ROS is dependent on their site of production on the electron transport chain in ischemic heart. Am. J. Cardiovasc. Dis. 6(3), 93-108 (2016).
[8]. Morita, S.y., Ueda, K., and Kitagawa, S. Enzymatic measurement of phosphatidic acid in cultured cells. J. Lipid Res. 50(9), 1945-1952 (2009).
[9]. Yang, Y., Zhao, J., Liu, P., et al. Glycerol-3-phosphate metabolism in wheat contributes to systemic acquired resistance against Puccinia striiformis f. sp. tritici. PLoS One 8(11), e81756 (2013).
[10]. Mugabo, Y., Zhao, S., Seifried, A., et al. Identification of a mammalian glycerol-3-phosphate phosphatase: Role in metabolism and signaling in pancreatic β-cells and hepatocytes. Proc. Natl. Acad. Sci. USA E430-439 (2016).
[11]. Tsuruoka, M., Hara, J., Hirayama, A., et al. Capillary electrophoresis-mass spectrometry-based metabolome analysis of serum and saliva from neurodegenerative dementia patients. Electrophoresis 34(19), 2865-2872 (2013).