Exact Mass: 786.5649

Exact Mass Matches: 786.5649

Found 500 metabolites which its exact mass value is equals to given mass value 786.5649, within given mass tolerance error 0.05 dalton. Try search metabolite list with more accurate mass tolerance error 0.01 dalton.

1-S-hexadecyl-2-O-[hexadecyl(hydroxy)phosphoryl]-1-thio-sn-glycero-3-phosphocholine

C40H86NO7P2S+ (786.56)

PA(20:0/20:3(8Z,11Z,14Z)-2OH(5,6))

[(2R)-2-{[(8Z,11Z,14Z)-5,6-dihydroxyicosa-8,11,14-trienoyl]oxy}-3-(icosanoyloxy)propoxy]phosphonic acid

C43H79O10P (786.5411)

PA(20:0/20:3(8Z,11Z,14Z)-2OH(5,6)) is an oxidized phosphatidic acid (PA). Oxidized phosphatidic acids are glycerophospholipids in which a phosphate moiety occupies a glycerol substitution site and at least one of the fatty acyl chains has undergone oxidation. As all oxidized lipids, oxidized phosphatidic acids belong to a group of biomolecules that have a role as signaling molecules. The biosynthesis of oxidized lipids is mediated by several enzymatic families, including cyclooxygenases (COX), lipoxygenases (LOX) and cytochrome P450s (CYP). Non-enzymatically oxidized lipids are produced by uncontrolled oxidation through free radicals and are considered harmful to human health (PMID: 33329396). As is the case with diacylglycerols, phosphatidic acids can have many different combinations of fatty acids of varying lengths, saturation and degrees of oxidation attached at the C-1 and C-2 positions. PA(20:0/20:3(8Z,11Z,14Z)-2OH(5,6)), in particular, consists of one chain of one eicosanoyl at the C-1 position and one chain of 5,6-dihydroxyeicosatrienoyl at the C-2 position. Phospholipids are ubiquitous in nature and are key components of the lipid bilayer of cells, as well as being involved in metabolism and signaling. Similarly to what occurs with phospholipids, the fatty acid distribution at the C-1 and C-2 positions of glycerol within oxidized phospholipids is continually in flux, owing to phospholipid degradation and the continuous phospholipid remodeling that occurs while these molecules are in membranes. Oxidized PAs can be synthesized via three different routes. In one route, the oxidized PA is synthetized de novo following the same mechanisms as for PAs but incorporating oxidized acyl chains (PMID: 33329396). An alternative is the transacylation of one of the non-oxidized acyl chains with an oxidized acylCoA (PMID: 33329396). The third pathway results from the oxidation of the acyl chain while still attached to the PA backbone, mainly through the action of LOX (PMID: 33329396).

PA(20:3(8Z,11Z,14Z)-2OH(5,6)/20:0)

[(2R)-3-{[(8Z,11Z,14Z)-5,6-dihydroxyicosa-8,11,14-trienoyl]oxy}-2-(icosanoyloxy)propoxy]phosphonic acid

C43H79O10P (786.5411)

PA(20:3(8Z,11Z,14Z)-2OH(5,6)/20:0) is an oxidized phosphatidic acid (PA). Oxidized phosphatidic acids are glycerophospholipids in which a phosphate moiety occupies a glycerol substitution site and at least one of the fatty acyl chains has undergone oxidation. As all oxidized lipids, oxidized phosphatidic acids belong to a group of biomolecules that have a role as signaling molecules. The biosynthesis of oxidized lipids is mediated by several enzymatic families, including cyclooxygenases (COX), lipoxygenases (LOX) and cytochrome P450s (CYP). Non-enzymatically oxidized lipids are produced by uncontrolled oxidation through free radicals and are considered harmful to human health (PMID: 33329396). As is the case with diacylglycerols, phosphatidic acids can have many different combinations of fatty acids of varying lengths, saturation and degrees of oxidation attached at the C-1 and C-2 positions. PA(20:3(8Z,11Z,14Z)-2OH(5,6)/20:0), in particular, consists of one chain of one 5,6-dihydroxyeicosatrienoyl at the C-1 position and one chain of eicosanoyl at the C-2 position. Phospholipids are ubiquitous in nature and are key components of the lipid bilayer of cells, as well as being involved in metabolism and signaling. Similarly to what occurs with phospholipids, the fatty acid distribution at the C-1 and C-2 positions of glycerol within oxidized phospholipids is continually in flux, owing to phospholipid degradation and the continuous phospholipid remodeling that occurs while these molecules are in membranes. Oxidized PAs can be synthesized via three different routes. In one route, the oxidized PA is synthetized de novo following the same mechanisms as for PAs but incorporating oxidized acyl chains (PMID: 33329396). An alternative is the transacylation of one of the non-oxidized acyl chains with an oxidized acylCoA (PMID: 33329396). The third pathway results from the oxidation of the acyl chain while still attached to the PA backbone, mainly through the action of LOX (PMID: 33329396).

PA(22:2(13Z,16Z)/18:1(12Z)-2OH(9,10))

[(2R)-2-{[(9S,10S,12Z)-9,10-dihydroxyoctadec-12-enoyl]oxy}-3-[(13Z,16Z)-docosa-13,16-dienoyloxy]propoxy]phosphonic acid

C43H79O10P (786.5411)

PA(22:2(13Z,16Z)/18:1(12Z)-2OH(9,10)) is an oxidized phosphatidic acid (PA). Oxidized phosphatidic acids are glycerophospholipids in which a phosphate moiety occupies a glycerol substitution site and at least one of the fatty acyl chains has undergone oxidation. As all oxidized lipids, oxidized phosphatidic acids belong to a group of biomolecules that have a role as signaling molecules. The biosynthesis of oxidized lipids is mediated by several enzymatic families, including cyclooxygenases (COX), lipoxygenases (LOX) and cytochrome P450s (CYP). Non-enzymatically oxidized lipids are produced by uncontrolled oxidation through free radicals and are considered harmful to human health (PMID: 33329396). As is the case with diacylglycerols, phosphatidic acids can have many different combinations of fatty acids of varying lengths, saturation and degrees of oxidation attached at the C-1 and C-2 positions. PA(22:2(13Z,16Z)/18:1(12Z)-2OH(9,10)), in particular, consists of one chain of one 13Z,16Z-docosadienoyl at the C-1 position and one chain of 9,10-hydroxy-octadecenoyl at the C-2 position. Phospholipids are ubiquitous in nature and are key components of the lipid bilayer of cells, as well as being involved in metabolism and signaling. Similarly to what occurs with phospholipids, the fatty acid distribution at the C-1 and C-2 positions of glycerol within oxidized phospholipids is continually in flux, owing to phospholipid degradation and the continuous phospholipid remodeling that occurs while these molecules are in membranes. Oxidized PAs can be synthesized via three different routes. In one route, the oxidized PA is synthetized de novo following the same mechanisms as for PAs but incorporating oxidized acyl chains (PMID: 33329396). An alternative is the transacylation of one of the non-oxidized acyl chains with an oxidized acylCoA (PMID: 33329396). The third pathway results from the oxidation of the acyl chain while still attached to the PA backbone, mainly through the action of LOX (PMID: 33329396).

PA(18:1(12Z)-2OH(9,10)/22:2(13Z,16Z))

[(2R)-3-{[(9R,10R,12Z)-9,10-dihydroxyoctadec-12-enoyl]oxy}-2-[(13Z,16Z)-docosa-13,16-dienoyloxy]propoxy]phosphonic acid

C43H79O10P (786.5411)

PA(18:1(12Z)-2OH(9,10)/22:2(13Z,16Z)) is an oxidized phosphatidic acid (PA). Oxidized phosphatidic acids are glycerophospholipids in which a phosphate moiety occupies a glycerol substitution site and at least one of the fatty acyl chains has undergone oxidation. As all oxidized lipids, oxidized phosphatidic acids belong to a group of biomolecules that have a role as signaling molecules. The biosynthesis of oxidized lipids is mediated by several enzymatic families, including cyclooxygenases (COX), lipoxygenases (LOX) and cytochrome P450s (CYP). Non-enzymatically oxidized lipids are produced by uncontrolled oxidation through free radicals and are considered harmful to human health (PMID: 33329396). As is the case with diacylglycerols, phosphatidic acids can have many different combinations of fatty acids of varying lengths, saturation and degrees of oxidation attached at the C-1 and C-2 positions. PA(18:1(12Z)-2OH(9,10)/22:2(13Z,16Z)), in particular, consists of one chain of one 9,10-hydroxy-octadecenoyl at the C-1 position and one chain of 13Z,16Z-docosadienoyl at the C-2 position. Phospholipids are ubiquitous in nature and are key components of the lipid bilayer of cells, as well as being involved in metabolism and signaling. Similarly to what occurs with phospholipids, the fatty acid distribution at the C-1 and C-2 positions of glycerol within oxidized phospholipids is continually in flux, owing to phospholipid degradation and the continuous phospholipid remodeling that occurs while these molecules are in membranes. Oxidized PAs can be synthesized via three different routes. In one route, the oxidized PA is synthetized de novo following the same mechanisms as for PAs but incorporating oxidized acyl chains (PMID: 33329396). An alternative is the transacylation of one of the non-oxidized acyl chains with an oxidized acylCoA (PMID: 33329396). The third pathway results from the oxidation of the acyl chain while still attached to the PA backbone, mainly through the action of LOX (PMID: 33329396).

PA(i-20:0/20:3(8Z,11Z,14Z)-2OH(5,6))

[(2R)-2-{[(8Z,11Z,14Z)-5,6-dihydroxyicosa-8,11,14-trienoyl]oxy}-3-[(18-methylnonadecanoyl)oxy]propoxy]phosphonic acid

C43H79O10P (786.5411)

PA(i-20:0/20:3(8Z,11Z,14Z)-2OH(5,6)) is an oxidized phosphatidic acid (PA). Oxidized phosphatidic acids are glycerophospholipids in which a phosphate moiety occupies a glycerol substitution site and at least one of the fatty acyl chains has undergone oxidation. As all oxidized lipids, oxidized phosphatidic acids belong to a group of biomolecules that have a role as signaling molecules. The biosynthesis of oxidized lipids is mediated by several enzymatic families, including cyclooxygenases (COX), lipoxygenases (LOX) and cytochrome P450s (CYP). Non-enzymatically oxidized lipids are produced by uncontrolled oxidation through free radicals and are considered harmful to human health (PMID: 33329396). As is the case with diacylglycerols, phosphatidic acids can have many different combinations of fatty acids of varying lengths, saturation and degrees of oxidation attached at the C-1 and C-2 positions. PA(i-20:0/20:3(8Z,11Z,14Z)-2OH(5,6)), in particular, consists of one chain of one 18-methylnonadecanoyl at the C-1 position and one chain of 5,6-dihydroxyeicosatrienoyl at the C-2 position. Phospholipids are ubiquitous in nature and are key components of the lipid bilayer of cells, as well as being involved in metabolism and signaling. Similarly to what occurs with phospholipids, the fatty acid distribution at the C-1 and C-2 positions of glycerol within oxidized phospholipids is continually in flux, owing to phospholipid degradation and the continuous phospholipid remodeling that occurs while these molecules are in membranes. Oxidized PAs can be synthesized via three different routes. In one route, the oxidized PA is synthetized de novo following the same mechanisms as for PAs but incorporating oxidized acyl chains (PMID: 33329396). An alternative is the transacylation of one of the non-oxidized acyl chains with an oxidized acylCoA (PMID: 33329396). The third pathway results from the oxidation of the acyl chain while still attached to the PA backbone, mainly through the action of LOX (PMID: 33329396).

PA(20:3(8Z,11Z,14Z)-2OH(5,6)/i-20:0)

[(2R)-3-{[(8Z,11Z,14Z)-5,6-dihydroxyicosa-8,11,14-trienoyl]oxy}-2-[(18-methylnonadecanoyl)oxy]propoxy]phosphonic acid

C43H79O10P (786.5411)

PA(20:3(8Z,11Z,14Z)-2OH(5,6)/i-20:0) is an oxidized phosphatidic acid (PA). Oxidized phosphatidic acids are glycerophospholipids in which a phosphate moiety occupies a glycerol substitution site and at least one of the fatty acyl chains has undergone oxidation. As all oxidized lipids, oxidized phosphatidic acids belong to a group of biomolecules that have a role as signaling molecules. The biosynthesis of oxidized lipids is mediated by several enzymatic families, including cyclooxygenases (COX), lipoxygenases (LOX) and cytochrome P450s (CYP). Non-enzymatically oxidized lipids are produced by uncontrolled oxidation through free radicals and are considered harmful to human health (PMID: 33329396). As is the case with diacylglycerols, phosphatidic acids can have many different combinations of fatty acids of varying lengths, saturation and degrees of oxidation attached at the C-1 and C-2 positions. PA(20:3(8Z,11Z,14Z)-2OH(5,6)/i-20:0), in particular, consists of one chain of one 5,6-dihydroxyeicosatrienoyl at the C-1 position and one chain of 18-methylnonadecanoyl at the C-2 position. Phospholipids are ubiquitous in nature and are key components of the lipid bilayer of cells, as well as being involved in metabolism and signaling. Similarly to what occurs with phospholipids, the fatty acid distribution at the C-1 and C-2 positions of glycerol within oxidized phospholipids is continually in flux, owing to phospholipid degradation and the continuous phospholipid remodeling that occurs while these molecules are in membranes. Oxidized PAs can be synthesized via three different routes. In one route, the oxidized PA is synthetized de novo following the same mechanisms as for PAs but incorporating oxidized acyl chains (PMID: 33329396). An alternative is the transacylation of one of the non-oxidized acyl chains with an oxidized acylCoA (PMID: 33329396). The third pathway results from the oxidation of the acyl chain while still attached to the PA backbone, mainly through the action of LOX (PMID: 33329396).

SM(d17:1/PGF2alpha)

(2-{[(2S,3R,4E)-2-[(5E)-7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-[(1E,3S)-3-hydroxyoct-1-en-1-yl]cyclopentyl]hept-5-enamido]-3-hydroxyheptadec-4-en-1-yl phosphono]oxy}ethyl)trimethylazanium

C42H79N2O9P (786.5523)

SM(d17:1/PGF2alpha) is a type of oxidized sphingolipid found in animal cell membranes. It usually consists of phosphorylcholine and ceramide. SM(d17:1/PGF2alpha) consists of a sphingosine backbone and a Prostaglandin F2alpha chain. In humans, sphingomyelin is the only membrane phospholipid not derived from glycerol. Like all sphingolipids, SM has a ceramide core (sphingosine bonded to a fatty acid via an amide linkage). In addition, it contains one polar head group, which is either phosphocholine or phosphoethanolamine. The plasma membrane of cells is highly enriched in sphingomyelin and is considered largely to be found in the exoplasmic leaflet of the cell membrane. However, there is some evidence that there may also be a sphingomyelin pool in the inner leaflet of the membrane. Moreover, neutral sphingomyelinase-2, an enzyme that breaks down sphingomyelin into ceramide, has been found to localize exclusively to the inner leaflet further suggesting that there may be sphingomyelin present there. Sphingomyelin can accumulate in a rare hereditary disease called Niemann-Pick Disease, types A and B. Niemann-Pick disease is a genetically-inherited disease caused by a deficiency in the enzyme sphingomyelinase, which causes the accumulation of sphingomyelin in spleen, liver, lungs, bone marrow, and the brain, causing irreversible neurological damage. SMs play a role in signal transduction. Sphingomyelins are synthesized by the transfer of phosphorylcholine from phosphatidylcholine to a ceramide in a reaction catalyzed by sphingomyelin synthase.

SM(d17:1/PGE1)

(2-{[(2S,3R,4E)-3-hydroxy-2-{7-[(1R,2R,3R)-3-hydroxy-2-[(1E,3S)-3-hydroxyoct-1-en-1-yl]-5-oxocyclopentyl]heptanamido}heptadec-4-en-1-yl phosphono]oxy}ethyl)trimethylazanium

C42H79N2O9P (786.5523)

SM(d17:1/PGE1) is a type of oxidized sphingolipid found in animal cell membranes. It usually consists of phosphorylcholine and ceramide. SM(d17:1/PGE1) consists of a sphingosine backbone and a Prostaglandin E1 chain. In humans, sphingomyelin is the only membrane phospholipid not derived from glycerol. Like all sphingolipids, SM has a ceramide core (sphingosine bonded to a fatty acid via an amide linkage). In addition, it contains one polar head group, which is either phosphocholine or phosphoethanolamine. The plasma membrane of cells is highly enriched in sphingomyelin and is considered largely to be found in the exoplasmic leaflet of the cell membrane. However, there is some evidence that there may also be a sphingomyelin pool in the inner leaflet of the membrane. Moreover, neutral sphingomyelinase-2, an enzyme that breaks down sphingomyelin into ceramide, has been found to localize exclusively to the inner leaflet further suggesting that there may be sphingomyelin present there. Sphingomyelin can accumulate in a rare hereditary disease called Niemann-Pick Disease, types A and B. Niemann-Pick disease is a genetically-inherited disease caused by a deficiency in the enzyme sphingomyelinase, which causes the accumulation of sphingomyelin in spleen, liver, lungs, bone marrow, and the brain, causing irreversible neurological damage. SMs play a role in signal transduction. Sphingomyelins are synthesized by the transfer of phosphorylcholine from phosphatidylcholine to a ceramide in a reaction catalyzed by sphingomyelin synthase.

SM(d17:1/PGD1)

(2-{[(2S,3R,4E)-3-hydroxy-2-{7-[(1R,2R,5S)-5-hydroxy-2-[(1E,3S)-3-hydroxyoct-1-en-1-yl]-3-oxocyclopentyl]heptanamido}heptadec-4-en-1-yl phosphono]oxy}ethyl)trimethylazanium

C42H79N2O9P (786.5523)

SM(d17:1/PGD1) is a type of oxidized sphingolipid found in animal cell membranes. It usually consists of phosphorylcholine and ceramide. SM(d17:1/PGD1) consists of a sphingosine backbone and a Prostaglandin D1 chain. In humans, sphingomyelin is the only membrane phospholipid not derived from glycerol. Like all sphingolipids, SM has a ceramide core (sphingosine bonded to a fatty acid via an amide linkage). In addition, it contains one polar head group, which is either phosphocholine or phosphoethanolamine. The plasma membrane of cells is highly enriched in sphingomyelin and is considered largely to be found in the exoplasmic leaflet of the cell membrane. However, there is some evidence that there may also be a sphingomyelin pool in the inner leaflet of the membrane. Moreover, neutral sphingomyelinase-2, an enzyme that breaks down sphingomyelin into ceramide, has been found to localize exclusively to the inner leaflet further suggesting that there may be sphingomyelin present there. Sphingomyelin can accumulate in a rare hereditary disease called Niemann-Pick Disease, types A and B. Niemann-Pick disease is a genetically-inherited disease caused by a deficiency in the enzyme sphingomyelinase, which causes the accumulation of sphingomyelin in spleen, liver, lungs, bone marrow, and the brain, causing irreversible neurological damage. SMs play a role in signal transduction. Sphingomyelins are synthesized by the transfer of phosphorylcholine from phosphatidylcholine to a ceramide in a reaction catalyzed by sphingomyelin synthase.

SM(d17:2(4E,8Z)/PGF1alpha)

(2-{[(2S,3R,4E,8Z)-2-{7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-[(1E,3S)-3-hydroxyoct-1-en-1-yl]cyclopentyl]heptanamido}-3-hydroxyheptadeca-4,8-dien-1-yl phosphono]oxy}ethyl)trimethylazanium

C42H79N2O9P (786.5523)

SM(d17:2(4E,8Z)/PGF1alpha) is a type of oxidized sphingolipid found in animal cell membranes. It usually consists of phosphorylcholine and ceramide. SM(d17:2(4E,8Z)/PGF1alpha) consists of a sphingosine backbone and a Prostaglandin F1alpha chain. In humans, sphingomyelin is the only membrane phospholipid not derived from glycerol. Like all sphingolipids, SM has a ceramide core (sphingosine bonded to a fatty acid via an amide linkage). In addition, it contains one polar head group, which is either phosphocholine or phosphoethanolamine. The plasma membrane of cells is highly enriched in sphingomyelin and is considered largely to be found in the exoplasmic leaflet of the cell membrane. However, there is some evidence that there may also be a sphingomyelin pool in the inner leaflet of the membrane. Moreover, neutral sphingomyelinase-2, an enzyme that breaks down sphingomyelin into ceramide, has been found to localize exclusively to the inner leaflet further suggesting that there may be sphingomyelin present there. Sphingomyelin can accumulate in a rare hereditary disease called Niemann-Pick Disease, types A and B. Niemann-Pick disease is a genetically-inherited disease caused by a deficiency in the enzyme sphingomyelinase, which causes the accumulation of sphingomyelin in spleen, liver, lungs, bone marrow, and the brain, causing irreversible neurological damage. SMs play a role in signal transduction. Sphingomyelins are synthesized by the transfer of phosphorylcholine from phosphatidylcholine to a ceramide in a reaction catalyzed by sphingomyelin synthase.

SM(d18:0/20:3(8Z,11Z,14Z)-2OH(5,6))

(2-{[(2S,3R)-2-[(8Z,11Z,14Z)-5,6-dihydroxyicosa-8,11,14-trienamido]-3-hydroxyoctadecyl phosphono]oxy}ethyl)trimethylazanium

C43H83N2O8P (786.5887)

SM(d18:0/20:3(8Z,11Z,14Z)-2OH(5,6)) is a type of oxidized sphingolipid found in animal cell membranes. It usually consists of phosphorylcholine and ceramide. SM(d18:0/20:3(8Z,11Z,14Z)-2OH(5,6)) consists of a sphingosine backbone and a 5,6-dihydroxyeicosatrienoyl chain. In humans, sphingomyelin is the only membrane phospholipid not derived from glycerol. Like all sphingolipids, SM has a ceramide core (sphingosine bonded to a fatty acid via an amide linkage). In addition, it contains one polar head group, which is either phosphocholine or phosphoethanolamine. The plasma membrane of cells is highly enriched in sphingomyelin and is considered largely to be found in the exoplasmic leaflet of the cell membrane. However, there is some evidence that there may also be a sphingomyelin pool in the inner leaflet of the membrane. Moreover, neutral sphingomyelinase-2, an enzyme that breaks down sphingomyelin into ceramide, has been found to localize exclusively to the inner leaflet further suggesting that there may be sphingomyelin present there. Sphingomyelin can accumulate in a rare hereditary disease called Niemann-Pick Disease, types A and B. Niemann-Pick disease is a genetically-inherited disease caused by a deficiency in the enzyme sphingomyelinase, which causes the accumulation of sphingomyelin in spleen, liver, lungs, bone marrow, and the brain, causing irreversible neurological damage. SMs play a role in signal transduction. Sphingomyelins are synthesized by the transfer of phosphorylcholine from phosphatidylcholine to a ceramide in a reaction catalyzed by sphingomyelin synthase.

SM(d19:1/5-iso PGF2VI)

(2-{[(2S,3R,4E)-2-[(3Z)-5-[(1S,2R,3R,5S)-3,5-dihydroxy-2-[(1E,3R)-3-hydroxyoct-1-en-1-yl]cyclopentyl]pent-3-enamido]-3-hydroxynonadec-4-en-1-yl phosphono]oxy}ethyl)trimethylazanium

C42H79N2O9P (786.5523)

SM(d19:1/5-iso PGF2VI) is a type of oxidized sphingolipid found in animal cell membranes. It usually consists of phosphorylcholine and ceramide. SM(d19:1/5-iso PGF2VI) consists of a sphingosine backbone and a 5-iso Prostaglandin F2alpha-VI chain. In humans, sphingomyelin is the only membrane phospholipid not derived from glycerol. Like all sphingolipids, SM has a ceramide core (sphingosine bonded to a fatty acid via an amide linkage). In addition, it contains one polar head group, which is either phosphocholine or phosphoethanolamine. The plasma membrane of cells is highly enriched in sphingomyelin and is considered largely to be found in the exoplasmic leaflet of the cell membrane. However, there is some evidence that there may also be a sphingomyelin pool in the inner leaflet of the membrane. Moreover, neutral sphingomyelinase-2, an enzyme that breaks down sphingomyelin into ceramide, has been found to localize exclusively to the inner leaflet further suggesting that there may be sphingomyelin present there. Sphingomyelin can accumulate in a rare hereditary disease called Niemann-Pick Disease, types A and B. Niemann-Pick disease is a genetically-inherited disease caused by a deficiency in the enzyme sphingomyelinase, which causes the accumulation of sphingomyelin in spleen, liver, lungs, bone marrow, and the brain, causing irreversible neurological damage. SMs play a role in signal transduction. Sphingomyelins are synthesized by the transfer of phosphorylcholine from phosphatidylcholine to a ceramide in a reaction catalyzed by sphingomyelin synthase.