Browsing Pathways

Phosphatidylethanolamines (PE) are a class of phospholipids that incorporate a phosphoric acid headgroup into a diacylglycerol backbone. They are the second most abundant phospholipid in eukaryotic cell membranes, and contrary to phosphatidylcholine, it is concentrated with phosphatidylserine in the cell membrane's inner leaflet. In Homo sapiens, there exist two phosphatidylethanolamine biosynthesis pathways. In the visualization, all enzymes that are dark green in colour are membrane-localized. The first pathway synthesizes phosphatidylethanolamine from ethanolamine via the Kennedy pathway. First, the cytosol-localized enzyme choline/ethanolamine kinase catalyzes the conversion of choline into phosphocholine. Second, choline-phosphate cytidylyltransferase, localized to the endoplasmic reticulum membrane, catalyzes the conversion of phosphocholine to CDP-choline. Last, choline/ethanolaminephosphotransferase catalyzes phosphatidylcholine biosynthesis from CDP-choline. It requires either magnesium or manganese ions as cofactors. Phosphatidylethanolamine is also synthesized from phosphatidylserine at the mitochondrial inner membrane by phosphatidylserine decarboxylase. Phosphatidylserine, itself, is synthesized using a base-exchange reaction with phosphatidylcholine. This reaction is catalyzed by phosphatidylserine synthase which is located in the endoplasmic reticulum membrane.

Phosphatidylethanolamines (PE) are a class of phospholipids that incorporate a phosphoric acid headgroup into a diacylglycerol backbone. They are the second most abundant phospholipid in eukaryotic cell membranes, and contrary to phosphatidylcholine, it is concentrated with phosphatidylserine in the cell membrane's inner leaflet. In Homo sapiens, there exist two phosphatidylethanolamine biosynthesis pathways. In the visualization, all enzymes that are dark green in colour are membrane-localized. The first pathway synthesizes phosphatidylethanolamine from ethanolamine via the Kennedy pathway. First, the cytosol-localized enzyme choline/ethanolamine kinase catalyzes the conversion of choline into phosphocholine. Second, choline-phosphate cytidylyltransferase, localized to the endoplasmic reticulum membrane, catalyzes the conversion of phosphocholine to CDP-choline. Last, choline/ethanolaminephosphotransferase catalyzes phosphatidylcholine biosynthesis from CDP-choline. It requires either magnesium or manganese ions as cofactors. Phosphatidylethanolamine is also synthesized from phosphatidylserine at the mitochondrial inner membrane by phosphatidylserine decarboxylase. Phosphatidylserine, itself, is synthesized using a base-exchange reaction with phosphatidylcholine. This reaction is catalyzed by phosphatidylserine synthase which is located in the endoplasmic reticulum membrane.

13-Methylpentacosanoylcarnitine is an acylcarnitine. The general role of acylcarnitines is to transport acyl-groups, organic acids and fatty acids, from the cytoplasm into the mitochondria so that they can be broken down to produce energy. As part of this process, 13-methylpentacosanoic acid is first transported into the cell via the long-chain fatty acid transport protein 1 (FATP1). Once inside the cell it undergoes a reaction to form an acyl-CoA derivative called 13-methylpentacosanoyl-CoA. This reaction is facilitated by the long-chain fatty-acid CoA ligase 1 protein, which adds a CoA moiety to appropriate acyl groups. Many acyl-CoA groups will then further react with other zwitterionic compounds such as carnitine (to form acylcarnitines) and amino acids (to form acyl amides). The carnitine needed to form acylcarnitines inside the cell is transported into the cell by the organic cation/carnitine transporter 2. In forming an acylcarnitine derivative, 13-methylpentacosanoyl-CoA reacts with L-carnitine to form 13-methylpentacosanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the 13-methylpentacosanoylcarnitine is moved into the mitochondrial intermembrane space. Following the reaction, the newly synthesized acylcarnitine is transported into the mitochondrial matrix by a mitochondrial carnitine/acylcarnitine carrier protein found in the mitochondrial inner membrane. Once in the matrix, 13-methylpentacosanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form 13-methylpentacosanoyl-CoA and L-carnitine. 13-Methylpentacosanoyl-CoA then enters into the mitochondrial beta-oxidation pathway to form aceytl-CoA. Acetyl-CoA can go on to enter the TCA cycle, or it can react with L-carnitine to form L-acetylcarnitine in a reaction catalyzed by Carnitine O-acetyltransferase. This reaction can occur in both directions, and L-acetylcarnitine and CoA can react to form acetyl-CoA and L-carnitine in certain circumstances. Finally, acetyl-CoA in the cytosol can be catalyzed by acetyl-CoA carboxylase 1 to form malonyl-CoA, which inhibits the action of carnitine O-palmitoyltransferase 1, thereby preventing 13-methylpentacosanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

18-Methylpentacosanoylcarnitine is an acylcarnitine. The general role of acylcarnitines is to transport acyl-groups, organic acids and fatty acids, from the cytoplasm into the mitochondria so that they can be broken down to produce energy. As part of this process, 18-methylpentacosanoic acid is first transported into the cell via the long-chain fatty acid transport protein 1 (FATP1). Once inside the cell it undergoes a reaction to form an acyl-CoA derivative called 18-methylpentacosanoyl-CoA. This reaction is facilitated by the long-chain fatty-acid CoA ligase 1 protein, which adds a CoA moiety to appropriate acyl groups. Many acyl-CoA groups will then further react with other zwitterionic compounds such as carnitine (to form acylcarnitines) and amino acids (to form acyl amides). The carnitine needed to form acylcarnitines inside the cell is transported into the cell by the organic cation/carnitine transporter 2. In forming an acylcarnitine derivative, 18-methylpentacosanoyl-CoA reacts with L-carnitine to form 18-methylpentacosanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the 18-methylpentacosanoylcarnitine is moved into the mitochondrial intermembrane space. Following the reaction, the newly synthesized acylcarnitine is transported into the mitochondrial matrix by a mitochondrial carnitine/acylcarnitine carrier protein found in the mitochondrial inner membrane. Once in the matrix, 18-methylpentacosanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form 18-methylpentacosanoyl-CoA and L-carnitine. 18-Methylpentacosanoyl-CoA then enters into the mitochondrial beta-oxidation pathway to form aceytl-CoA. Acetyl-CoA can go on to enter the TCA cycle, or it can react with L-carnitine to form L-acetylcarnitine in a reaction catalyzed by Carnitine O-acetyltransferase. This reaction can occur in both directions, and L-acetylcarnitine and CoA can react to form acetyl-CoA and L-carnitine in certain circumstances. Finally, acetyl-CoA in the cytosol can be catalyzed by acetyl-CoA carboxylase 1 to form malonyl-CoA, which inhibits the action of carnitine O-palmitoyltransferase 1, thereby preventing 18-methylpentacosanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

3-Methylpentanoylcarnitine is an acylcarnitine. The general role of acylcarnitines is to transport acyl-groups, organic acids and fatty acids, from the cytoplasm into the mitochondria so that they can be broken down to produce energy. As part of this process, 3-methylpentanoic acid is first transported into the cell via the long-chain fatty acid transport protein 1 (FATP1). Once inside the cell it undergoes a reaction to form an acyl-CoA derivative called 3-methylpentanoyl-CoA. This reaction is facilitated by the long-chain fatty-acid CoA ligase 1 protein, which adds a CoA moiety to appropriate acyl groups. Many acyl-CoA groups will then further react with other zwitterionic compounds such as carnitine (to form acylcarnitines) and amino acids (to form acyl amides). The carnitine needed to form acylcarnitines inside the cell is transported into the cell by the organic cation/carnitine transporter 2. In forming an acylcarnitine derivative, 3-methylpentanoyl-CoA reacts with L-carnitine to form 3-methylpentanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the 3-methylpentanoylcarnitine is moved into the mitochondrial intermembrane space. Following the reaction, the newly synthesized acylcarnitine is transported into the mitochondrial matrix by a mitochondrial carnitine/acylcarnitine carrier protein found in the mitochondrial inner membrane. Once in the matrix, 3-methylpentanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form 3-methylpentanoyl-CoA and L-carnitine. 3-Methylpentanoyl-CoA then enters into the mitochondrial beta-oxidation pathway to form aceytl-CoA. Acetyl-CoA can go on to enter the TCA cycle, or it can react with L-carnitine to form L-acetylcarnitine in a reaction catalyzed by Carnitine O-acetyltransferase. This reaction can occur in both directions, and L-acetylcarnitine and CoA can react to form acetyl-CoA and L-carnitine in certain circumstances. Finally, acetyl-CoA in the cytosol can be catalyzed by acetyl-CoA carboxylase 1 to form malonyl-CoA, which inhibits the action of carnitine O-palmitoyltransferase 1, thereby preventing 3-methylpentanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

3-Methylhexanoylcarnitine is an acylcarnitine. The general role of acylcarnitines is to transport acyl-groups, organic acids and fatty acids, from the cytoplasm into the mitochondria so that they can be broken down to produce energy. As part of this process, 3-methylhexanoic acid is first transported into the cell via the long-chain fatty acid transport protein 1 (FATP1). Once inside the cell it undergoes a reaction to form an acyl-CoA derivative called 3-methylhexanoyl-CoA. This reaction is facilitated by the long-chain fatty-acid CoA ligase 1 protein, which adds a CoA moiety to appropriate acyl groups. Many acyl-CoA groups will then further react with other zwitterionic compounds such as carnitine (to form acylcarnitines) and amino acids (to form acyl amides). The carnitine needed to form acylcarnitines inside the cell is transported into the cell by the organic cation/carnitine transporter 2. In forming an acylcarnitine derivative, 3-methylhexanoyl-CoA reacts with L-carnitine to form 3-methylhexanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the 3-methylhexanoylcarnitine is moved into the mitochondrial intermembrane space. Following the reaction, the newly synthesized acylcarnitine is transported into the mitochondrial matrix by a mitochondrial carnitine/acylcarnitine carrier protein found in the mitochondrial inner membrane. Once in the matrix, 3-methylhexanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form 3-methylhexanoyl-CoA and L-carnitine. 3-Methylhexanoyl-CoA then enters into the mitochondrial beta-oxidation pathway to form aceytl-CoA. Acetyl-CoA can go on to enter the TCA cycle, or it can react with L-carnitine to form L-acetylcarnitine in a reaction catalyzed by Carnitine O-acetyltransferase. This reaction can occur in both directions, and L-acetylcarnitine and CoA can react to form acetyl-CoA and L-carnitine in certain circumstances. Finally, acetyl-CoA in the cytosol can be catalyzed by acetyl-CoA carboxylase 1 to form malonyl-CoA, which inhibits the action of carnitine O-palmitoyltransferase 1, thereby preventing 3-methylhexanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

2,2-dimethylpentanedioylcarnitine is an acylcarnitine. The general role of acylcarnitines is to transport acyl-groups, organic acids and fatty acids, from the cytoplasm into the mitochondria so that they can be broken down to produce energy. As part of this process, 2,2-dimethylpentanedioic acid is first transported into the cell via the long-chain fatty acid transport protein 1 (FATP1). Once inside the cell it undergoes a reaction to form an acyl-CoA derivative called 2,2-dimethylpentanedioyl-CoA. This reaction is facilitated by the long-chain fatty-acid CoA ligase 1 protein, which adds a CoA moiety to appropriate acyl groups. Many acyl-CoA groups will then further react with other zwitterionic compounds such as carnitine (to form acylcarnitines) and amino acids (to form acyl amides). The carnitine needed to form acylcarnitines inside the cell is transported into the cell by the organic cation/carnitine transporter 2. In forming an acylcarnitine derivative, 2,2-dimethylpentanedioyl-CoA reacts with L-carnitine to form 2,2-dimethylpentanedioylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the 2,2-dimethylpentanedioylcarnitine is moved into the mitochondrial intermembrane space. Following the reaction, the newly synthesized acylcarnitine is transported into the mitochondrial matrix by a mitochondrial carnitine/acylcarnitine carrier protein found in the mitochondrial inner membrane. Once in the matrix, 2,2-dimethylpentanedioylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form 2,2-dimethylpentanedioyl-CoA and L-carnitine. 2,2-dimethylpentanedioyl-CoA then enters into the mitochondrial beta-oxidation pathway to form aceytl-CoA. Acetyl-CoA can go on to enter the TCA cycle, or it can react with L-carnitine to form L-acetylcarnitine in a reaction catalyzed by Carnitine O-acetyltransferase. This reaction can occur in both directions, and L-acetylcarnitine and CoA can react to form acetyl-CoA and L-carnitine in certain circumstances. Finally, acetyl-CoA in the cytosol can be catalyzed by acetyl-CoA carboxylase 1 to form malonyl-CoA, which inhibits the action of carnitine O-palmitoyltransferase 1, thereby preventing 2,2-dimethylpentanedioylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

3,4-dimethylidenehexanedioylcarnitine is an acylcarnitine. The general role of acylcarnitines is to transport acyl-groups, organic acids and fatty acids, from the cytoplasm into the mitochondria so that they can be broken down to produce energy. As part of this process, 3,4-dimethylidenehexanedioic acid is first transported into the cell via the long-chain fatty acid transport protein 1 (FATP1). Once inside the cell it undergoes a reaction to form an acyl-CoA derivative called 3,4-dimethylidenehexanedioyl-CoA. This reaction is facilitated by the long-chain fatty-acid CoA ligase 1 protein, which adds a CoA moiety to appropriate acyl groups. Many acyl-CoA groups will then further react with other zwitterionic compounds such as carnitine (to form acylcarnitines) and amino acids (to form acyl amides). The carnitine needed to form acylcarnitines inside the cell is transported into the cell by the organic cation/carnitine transporter 2. In forming an acylcarnitine derivative, 3,4-dimethylidenehexanedioyl-CoA reacts with L-carnitine to form 3,4-dimethylidenehexanedioylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the 3,4-dimethylidenehexanedioylcarnitine is moved into the mitochondrial intermembrane space. Following the reaction, the newly synthesized acylcarnitine is transported into the mitochondrial matrix by a mitochondrial carnitine/acylcarnitine carrier protein found in the mitochondrial inner membrane. Once in the matrix, 3,4-dimethylidenehexanedioylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form 3,4-dimethylidenehexanedioyl-CoA and L-carnitine. 3,4-dimethylidenehexanedioyl-CoA then enters into the mitochondrial beta-oxidation pathway to form aceytl-CoA. Acetyl-CoA can go on to enter the TCA cycle, or it can react with L-carnitine to form L-acetylcarnitine in a reaction catalyzed by Carnitine O-acetyltransferase. This reaction can occur in both directions, and L-acetylcarnitine and CoA can react to form acetyl-CoA and L-carnitine in certain circumstances. Finally, acetyl-CoA in the cytosol can be catalyzed by acetyl-CoA carboxylase 1 to form malonyl-CoA, which inhibits the action of carnitine O-palmitoyltransferase 1, thereby preventing 3,4-dimethylidenehexanedioylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

3-methyloctanedioylcarnitine is an acylcarnitine. The general role of acylcarnitines is to transport acyl-groups, organic acids and fatty acids, from the cytoplasm into the mitochondria so that they can be broken down to produce energy. As part of this process, 3-methyloctanedioic acid is first transported into the cell via the long-chain fatty acid transport protein 1 (FATP1). Once inside the cell it undergoes a reaction to form an acyl-CoA derivative called 3-methyloctanedioyl-CoA. This reaction is facilitated by the long-chain fatty-acid CoA ligase 1 protein, which adds a CoA moiety to appropriate acyl groups. Many acyl-CoA groups will then further react with other zwitterionic compounds such as carnitine (to form acylcarnitines) and amino acids (to form acyl amides). The carnitine needed to form acylcarnitines inside the cell is transported into the cell by the organic cation/carnitine transporter 2. In forming an acylcarnitine derivative, 3-methyloctanedioyl-CoA reacts with L-carnitine to form 3-methyloctanedioylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the 3-methyloctanedioylcarnitine is moved into the mitochondrial intermembrane space. Following the reaction, the newly synthesized acylcarnitine is transported into the mitochondrial matrix by a mitochondrial carnitine/acylcarnitine carrier protein found in the mitochondrial inner membrane. Once in the matrix, 3-methyloctanedioylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form 3-methyloctanedioyl-CoA and L-carnitine. 3-methyloctanedioyl-CoA then enters into the mitochondrial beta-oxidation pathway to form aceytl-CoA. Acetyl-CoA can go on to enter the TCA cycle, or it can react with L-carnitine to form L-acetylcarnitine in a reaction catalyzed by Carnitine O-acetyltransferase. This reaction can occur in both directions, and L-acetylcarnitine and CoA can react to form acetyl-CoA and L-carnitine in certain circumstances. Finally, acetyl-CoA in the cytosol can be catalyzed by acetyl-CoA carboxylase 1 to form malonyl-CoA, which inhibits the action of carnitine O-palmitoyltransferase 1, thereby preventing 3-methyloctanedioylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

2-Hydroxydecanoylcarnitine is an acylcarnitine. The general role of acylcarnitines is to transport acyl-groups, organic acids and fatty acids, from the cytoplasm into the mitochondria so that they can be broken down to produce energy. As part of this process, 2-hydroxydecanoic acid is first transported into the cell via the long-chain fatty acid transport protein 1 (FATP1). Once inside the cell it undergoes a reaction to form an acyl-CoA derivative called 2-hydroxydecanoyl-CoA. This reaction is facilitated by the long-chain fatty-acid CoA ligase 1 protein, which adds a CoA moiety to appropriate acyl groups. Many acyl-CoA groups will then further react with other zwitterionic compounds such as carnitine (to form acylcarnitines) and amino acids (to form acyl amides). The carnitine needed to form acylcarnitines inside the cell is transported into the cell by the organic cation/carnitine transporter 2. In forming an acylcarnitine derivative, 2-hydroxydecanoyl-CoA reacts with L-carnitine to form 2-hydroxydecanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the 2-hydroxydecanoylcarnitine is moved into the mitochondrial intermembrane space. Following the reaction, the newly synthesized acylcarnitine is transported into the mitochondrial matrix by a mitochondrial carnitine/acylcarnitine carrier protein found in the mitochondrial inner membrane. Once in the matrix, 2-hydroxydecanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form 2-hydroxydecanoyl-CoA and L-carnitine. 2-Hydroxydecanoyl-CoA then enters into the mitochondrial beta-oxidation pathway to form aceytl-CoA. Acetyl-CoA can go on to enter the TCA cycle, or it can react with L-carnitine to form L-acetylcarnitine in a reaction catalyzed by Carnitine O-acetyltransferase. This reaction can occur in both directions, and L-acetylcarnitine and CoA can react to form acetyl-CoA and L-carnitine in certain circumstances. Finally, acetyl-CoA in the cytosol can be catalyzed by acetyl-CoA carboxylase 1 to form malonyl-CoA, which inhibits the action of carnitine O-palmitoyltransferase 1, thereby preventing 2-hydroxydecanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.