Pathways

(2S,3R)-3-hydroxy-2-methylpentanedioylcarnitine 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, (2S,3R)-3-hydroxy-2-methylpentanedioic 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 (2S,3R)-3-hydroxy-2-methylpentanedioyl-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, (2S,3R)-3-hydroxy-2-methylpentanedioyl-CoA reacts with L-carnitine to form (2S,3R)-3-hydroxy-2-methylpentanedioylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the (2S,3R)-3-hydroxy-2-methylpentanedioylcarnitine 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, (2S,3R)-3-hydroxy-2-methylpentanedioylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form (2S,3R)-3-hydroxy-2-methylpentanedioyl-CoA and L-carnitine. (2S,3R)-3-hydroxy-2-methylpentanedioyl-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 (2S,3R)-3-hydroxy-2-methylpentanedioylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

(2S,3R)-3-Hydroxy-2-methylbutanoylcarnitine 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, (2S,3R)-3-hydroxy-2-methylbutanoic 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 (2S,3R)-3-hydroxy-2-methylbutanoyl-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, (2S,3R)-3-hydroxy-2-methylbutanoyl-CoA reacts with L-carnitine to form (2S,3R)-3-hydroxy-2-methylbutanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the (2S,3R)-3-hydroxy-2-methylbutanoylcarnitine 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, (2S,3R)-3-hydroxy-2-methylbutanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form (2S,3R)-3-hydroxy-2-methylbutanoyl-CoA and L-carnitine. (2S,3R)-3-Hydroxy-2-methylbutanoyl-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 (2S,3R)-3-hydroxy-2-methylbutanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

(2S)-2-hydroxyoctadecanoylcarnitine 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, (2S)-2-hydroxyoctadecanoic 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 (2S)-2-hydroxyoctadecanoyl-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, (2S)-2-hydroxyoctadecanoyl-CoA reacts with L-carnitine to form (2S)-2-hydroxyoctadecanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the (2S)-2-hydroxyoctadecanoylcarnitine 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, (2S)-2-hydroxyoctadecanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form (2S)-2-hydroxyoctadecanoyl-CoA and L-carnitine. (2S)-2-hydroxyoctadecanoyl-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 (2S)-2-hydroxyoctadecanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

(2S)-2-hydroxyhexadecanoylcarnitine 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, (2S)-2-hydroxyhexadecanoic 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 (2S)-2-hydroxyhexadecanoyl-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, (2S)-2-hydroxyhexadecanoyl-CoA reacts with L-carnitine to form (2S)-2-hydroxyhexadecanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the (2S)-2-hydroxyhexadecanoylcarnitine 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, (2S)-2-hydroxyhexadecanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form (2S)-2-hydroxyhexadecanoyl-CoA and L-carnitine. (2S)-2-hydroxyhexadecanoyl-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 (2S)-2-hydroxyhexadecanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

(2S)-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, (2S)-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 (2S)-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, (2S)-2-hydroxydecanoyl-CoA reacts with L-carnitine to form (2S)-2-hydroxydecanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the (2S)-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, (2S)-2-hydroxydecanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form (2S)-2-hydroxydecanoyl-CoA and L-carnitine. (2S)-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 (2S)-2-hydroxydecanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

(2S)-2-hydroxy-2-(propan-2-yl)butanedioylcarnitine 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, (2S)-2-hydroxy-2-(propan-2-yl)butanedioic 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 (2S)-2-hydroxy-2-(propan-2-yl)butanedioyl-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, (2S)-2-hydroxy-2-(propan-2-yl)butanedioyl-CoA reacts with L-carnitine to form (2S)-2-hydroxy-2-(propan-2-yl)butanedioylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the (2S)-2-hydroxy-2-(propan-2-yl)butanedioylcarnitine 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, (2S)-2-hydroxy-2-(propan-2-yl)butanedioylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form (2S)-2-hydroxy-2-(propan-2-yl)butanedioyl-CoA and L-carnitine. (2S)-2-hydroxy-2-(propan-2-yl)butanedioyl-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 (2S)-2-hydroxy-2-(propan-2-yl)butanedioylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

(2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl]-2-[(hydroxymethyl)sulfanyl]ethyl]carbamoyl}butanoylcarnitine 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, (2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl]-2-[(hydroxymethyl)sulfanyl]ethyl]carbamoyl}butanoic 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 (2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl]-2-[(hydroxymethyl)sulfanyl]ethyl]carbamoyl}butanoyl-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, (2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl]-2-[(hydroxymethyl)sulfanyl]ethyl]carbamoyl}butanoyl-CoA reacts with L-carnitine to form (2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl]-2-[(hydroxymethyl)sulfanyl]ethyl]carbamoyl}butanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the (2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl]-2-[(hydroxymethyl)sulfanyl]ethyl]carbamoyl}butanoylcarnitine 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, (2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl]-2-[(hydroxymethyl)sulfanyl]ethyl]carbamoyl}butanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form (2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl]-2-[(hydroxymethyl)sulfanyl]ethyl]carbamoyl}butanoyl-CoA and L-carnitine. (2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl]-2-[(hydroxymethyl)sulfanyl]ethyl]carbamoyl}butanoyl-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 (2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl]-2-[(hydroxymethyl)sulfanyl]ethyl]carbamoyl}butanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

(2R,3S)-3-Hydroxy-2-methylbutanoylcarnitine 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, (2R,3S)-3-hydroxy-2-methylbutanoic 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 (2R,3S)-3-hydroxy-2-methylbutanoyl-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, (2R,3S)-3-hydroxy-2-methylbutanoyl-CoA reacts with L-carnitine to form (2R,3S)-3-hydroxy-2-methylbutanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the (2R,3S)-3-hydroxy-2-methylbutanoylcarnitine 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, (2R,3S)-3-hydroxy-2-methylbutanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form (2R,3S)-3-hydroxy-2-methylbutanoyl-CoA and L-carnitine. (2R,3S)-3-Hydroxy-2-methylbutanoyl-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 (2R,3S)-3-hydroxy-2-methylbutanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

(2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoylcarnitine 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, (2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoic 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 (2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoyl-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, (2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoyl-CoA reacts with L-carnitine to form (2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the (2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoylcarnitine 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, (2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form (2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoyl-CoA and L-carnitine. (2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoyl-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 (2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.

(2R,3R)-3-Hydroxy-2-methylbutanoylcarnitine 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, (2R,3R)-3-hydroxy-2-methylbutanoic 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 (2R,3R)-3-hydroxy-2-methylbutanoyl-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, (2R,3R)-3-hydroxy-2-methylbutanoyl-CoA reacts with L-carnitine to form (2R,3R)-3-hydroxy-2-methylbutanoylcarnitine. This reaction is catalyzed by carnitine O-palmitoyltransferase. This enzyme resides in the mitochondrial outer membrane. While this reaction takes place, the (2R,3R)-3-hydroxy-2-methylbutanoylcarnitine 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, (2R,3R)-3-hydroxy-2-methylbutanoylcarnitine can react with the carnitine O-palmitoyltransferase 2 enzyme found in the mitochondrial inner membrane to once again form (2R,3R)-3-hydroxy-2-methylbutanoyl-CoA and L-carnitine. (2R,3R)-3-Hydroxy-2-methylbutanoyl-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 (2R,3R)-3-hydroxy-2-methylbutanoylcarnitine from forming and thereby preventing it from being transported into the mitochondria.