Intra-day precision and accuracy in RBL-2H3 and Jurkat T-cell extracts.

<p>^an = 5.</p><p>^b[Standard deviation/ measured mean concentration] x 100.</p><p>^c[Measured mean concentration/ nominal concentration] x 100.</p><p>Intra-day precision and accuracy in RBL-2H3 and Jurkat T-cell extracts.</p

Inter-day precision and accuracy in RBL-2H3 and Jurkat T-cell extracts.

<p>^an = 3 days with five replicates per day.</p><p>^b[Standard deviation/ measured mean concentration] x 100.</p><p>^c[Measured mean concentration/ nominal concentration] x 100.</p><p>Inter-day precision and accuracy in RBL-2H3 and Jurkat T-cell extracts.</p

Representative LC-MRM chromatograms.

<p>(A) LOQ (3 ng/ml) of Gro<i>P</i>Ins in water. (B) Gro<i>P</i>Ins at the highest standard concentration (3,000 ng/ml) in water. (C) Blank sample after injection of the highest concentration of Gro<i>P</i>Ins (3,000 ng/ml).</p

Intra-day and inter-day precision and accuracy in Raw 264.7 cell extract.

<p>^an = 5.</p><p>^bn = 3 days with five replicates per day.</p><p>^c[Standard deviation/ measured mean concentration] x 100.</p><p>^d[Measured mean concentration/ nominal concentration] x 100.</p><p>Intra-day and inter-day precision and accuracy in Raw 264.7 cell extract.</p

Table_2_The Structure and Function of Acylglycerophosphate Acyltransferase 4/ Lysophosphatidic Acid Acyltransferase Delta (AGPAT4/LPAATδ).xlsx

Lipid-modifying enzymes serve crucial roles in cellular processes such as signal transduction (producing lipid-derived second messengers), intracellular membrane transport (facilitating membrane remodeling needed for membrane fusion/fission), and protein clustering (organizing lipid domains as anchoring platforms). The lipid products crucial in these processes can derive from different metabolic pathways, thus it is essential to know the localization, substrate specificity, deriving products (and their function) of all lipid-modifying enzymes. Here we discuss an emerging family of these enzymes, the lysophosphatidic acid acyltransferases (LPAATs), also known as acylglycerophosphate acyltransferases (AGPATs), that produce phosphatidic acid (PA) having as substrates lysophosphatidic acid (LPA) and acyl-CoA. Eleven LPAAT/AGPAT enzymes have been identified in mice and humans based on sequence homologies, and their localization, specific substrates and functions explored. We focus on one member of the family, LPAATδ, a protein expressed mainly in brain and in muscle (though to a lesser extent in other tissues); while at the cellular level it is localized at the trans-Golgi network membranes and at the mitochondrial outer membranes. LPAATδ is a physiologically essential enzyme since mice knocked-out for Lpaatδ show severe dysfunctions including cognitive impairment, impaired force contractility and altered white adipose tissue. The LPAATδ physiological roles are related to the formation of its product PA. PA is a multifunctional lipid involved in cell signaling as well as in membrane remodeling. In particular, the LPAATδ-catalyzed conversion of LPA (inverted-cone-shaped lipid) to PA (cone-shaped lipid) is considered a mechanism of deformation of the bilayer that favors membrane fission. Indeed, LPAATδ is an essential component of the fission-inducing machinery driven by the protein BARS. In this process, a protein-tripartite complex (BARS/14-3-3γ/phosphoinositide kinase PI4KIIIβ) is recruited at the trans-Golgi network, at the sites where membrane fission is to occur; there, LPAATδ directly interacts with BARS and is activated by BARS. The resulting formation of PA is essential for membrane fission occurring at those spots. Also in mitochondria PA formation has been related to fusion/fission events. Since PA is formed by various enzymatic pathways in different cell compartments, the BARS-LPAATδ interaction indicates the relevance of lipid-modifying enzymes acting exactly where their products are needed (i.e., PA at the Golgi membranes).</p

Matrix effect in Raw 264.7, RBL-2H3 and Jurkat T-cell extracts.

<p>^aEach point is based on five replicates.</p><p>Matrix effect in Raw 264.7, RBL-2H3 and Jurkat T-cell extracts.</p

Linearity and Gro<i>P</i>Ins concentration in RBL-2H3 and Jurkat T-cell extracts by internal standard calibration and standard addition method.

<p>^aAnalyses were performed in triplicate (n = 5). Values are expressed as mean ± SD.</p><p>Linearity and Gro<i>P</i>Ins concentration in RBL-2H3 and Jurkat T-cell extracts by internal standard calibration and standard addition method.</p

Representative LC-MRM chromatogram of Gro<i>P</i>Ins and of the IS.

<p>(A) Cell extract of Raw264.7. (B) Cell extract of Raw 264.7 spiked with standard Gro<i>P</i>Ins.</p

Linearity of Gro<i>P</i>Ins and analyte concentration in Raw 264.7 cell extract.

<p>(A) Standard addition calibration in matrix. (B) Internal standard calibration in water. Error bars are expressed as SD.</p

Table_3_The Structure and Function of Acylglycerophosphate Acyltransferase 4/ Lysophosphatidic Acid Acyltransferase Delta (AGPAT4/LPAATδ).xlsx

Lipid-modifying enzymes serve crucial roles in cellular processes such as signal transduction (producing lipid-derived second messengers), intracellular membrane transport (facilitating membrane remodeling needed for membrane fusion/fission), and protein clustering (organizing lipid domains as anchoring platforms). The lipid products crucial in these processes can derive from different metabolic pathways, thus it is essential to know the localization, substrate specificity, deriving products (and their function) of all lipid-modifying enzymes. Here we discuss an emerging family of these enzymes, the lysophosphatidic acid acyltransferases (LPAATs), also known as acylglycerophosphate acyltransferases (AGPATs), that produce phosphatidic acid (PA) having as substrates lysophosphatidic acid (LPA) and acyl-CoA. Eleven LPAAT/AGPAT enzymes have been identified in mice and humans based on sequence homologies, and their localization, specific substrates and functions explored. We focus on one member of the family, LPAATδ, a protein expressed mainly in brain and in muscle (though to a lesser extent in other tissues); while at the cellular level it is localized at the trans-Golgi network membranes and at the mitochondrial outer membranes. LPAATδ is a physiologically essential enzyme since mice knocked-out for Lpaatδ show severe dysfunctions including cognitive impairment, impaired force contractility and altered white adipose tissue. The LPAATδ physiological roles are related to the formation of its product PA. PA is a multifunctional lipid involved in cell signaling as well as in membrane remodeling. In particular, the LPAATδ-catalyzed conversion of LPA (inverted-cone-shaped lipid) to PA (cone-shaped lipid) is considered a mechanism of deformation of the bilayer that favors membrane fission. Indeed, LPAATδ is an essential component of the fission-inducing machinery driven by the protein BARS. In this process, a protein-tripartite complex (BARS/14-3-3γ/phosphoinositide kinase PI4KIIIβ) is recruited at the trans-Golgi network, at the sites where membrane fission is to occur; there, LPAATδ directly interacts with BARS and is activated by BARS. The resulting formation of PA is essential for membrane fission occurring at those spots. Also in mitochondria PA formation has been related to fusion/fission events. Since PA is formed by various enzymatic pathways in different cell compartments, the BARS-LPAATδ interaction indicates the relevance of lipid-modifying enzymes acting exactly where their products are needed (i.e., PA at the Golgi membranes).</p