PM20D1

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0016811 hydrolase activity, acting on carbon-nitrogen (but not peptide) bonds, in linear amides	EXP PMID:27374330 The Secreted Enzyme PM20D1 Regulates Lipidated Amino Acid Un...	ACCEPT	Summary: ACCEPT. This is the core molecular function of PM20D1. The enzyme hydrolyzes N-acyl amino acids (linear amides) to release fatty acids and amino acids. This is directly demonstrated with purified human PM20D1 in vitro. Supporting Evidence: PMID:27374330 We demonstrate that PM20D1 is a bidirectional enzyme in vitro, catalyzing both the condensation of fatty acids and amino acids to generate N-acyl amino acids and also the reverse hydrolytic reaction.
GO:0016811 hydrolase activity, acting on carbon-nitrogen (but not peptide) bonds, in linear amides	IBA GO_REF:0000033	ACCEPT	Summary: ACCEPT. Consistent with EXP evidence. IBA annotation from phylogenetic inference supports the experimentally demonstrated hydrolase activity. Under assay conditions, PM20D1 exhibited ~94% hydrolase conversion, demonstrating robust hydrolytic activity on N-acyl amino acid substrates. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-falcon.md Under assay conditions, PM20D1 exhibited markedly higher hydrolase conversion (~94%) than synthase conversion (~1.2%), highlighting strong hydrolase activity and more selective synthetic activity.
GO:0016811 hydrolase activity, acting on carbon-nitrogen (but not peptide) bonds, in linear amides	IEA GO_REF:0000120	ACCEPT	Summary: ACCEPT. Consistent with EXP evidence. IEA annotation supports the experimentally demonstrated hydrolase activity. The hydrolase activity of PM20D1 appears to be more promiscuous than the synthase activity, efficiently hydrolyzing all N-oleoyl amino acids tested. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-cyberian.md The hydrolase activity of PM20D1 appears to be more promiscuous than the synthase activity. PM20D1 efficiently hydrolyzes all N-oleoyl amino acids tested, including those with amino acids that are poorly utilized as synthase substrates.
GO:0004046 aminoacylase activity	IEA GO_REF:0000120	ACCEPT	Summary: ACCEPT. PM20D1 has aminoacylase activity (EC 3.5.1.14), hydrolyzing N-acyl-L-amino acids to carboxylate and L-amino acid. This is consistent with the experimentally demonstrated hydrolysis of N-oleoyl-phenylalanine and other N-acyl amino acids. Supporting Evidence: PMID:27374330 We demonstrate that PM20D1 is a bidirectional enzyme in vitro, catalyzing both the condensation of fatty acids and amino acids to generate N-acyl amino acids and also the reverse hydrolytic reaction.
GO:0016787 hydrolase activity	IEA GO_REF:0000120	KEEP AS NON CORE	Summary: KEEP_AS_NON_CORE. This is too general - the more specific term GO:0016811 (hydrolase activity, acting on C-N bonds in linear amides) better captures PM20D1's function. Reason: Too general; GO:0016811 is more specific and accurate
GO:0008233 peptidase activity	IEA GO_REF:0000043	REMOVE	Summary: REMOVE. This is a misleading annotation. Although PM20D1 belongs to the M20 peptidase family by sequence homology, it does NOT function as a peptidase. PM20D1 represents a textbook case of enzymatic neofunctionalization where it has completely abandoned its ancestral peptide-cleaving function. It hydrolyzes N-acyl amino acids (fatty acid-amino acid conjugates), not peptide bonds. The substrate is not a peptide but an N-fatty-acyl amino acid. Reason: PM20D1 does not cleave peptide bonds. It hydrolyzes N-acyl amino acids where a fatty acid is conjugated to a free amino acid, not a peptide. The M20 domain annotation is misleading for this enzyme's actual function. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-perplexity.md PM20D1 has completely abandoned its ancestral peptide-cleaving function. Instead, it evolved into a bidirectional enzyme that synthesizes and hydrolyzes N-acyl amino acids.
GO:0016829 lyase activity	IEA GO_REF:0000043	REMOVE	Summary: REMOVE. PM20D1 is a hydrolase/synthase, not a lyase. The synthase reaction requires water as a leaving group (condensation), and the hydrolase reaction requires water as a substrate. These are hydrolase (EC 3.5.1) reactions, not lyase reactions. PM20D1 is assigned EC 3.5.1.14 (aminoacylase) and EC 3.5.1.114. Reason: Incorrect enzyme class. PM20D1 is a hydrolase (EC 3.5.1.14, 3.5.1.114), not a lyase. Supporting Evidence: PMID:27374330 We demonstrate that PM20D1 is a bidirectional enzyme in vitro, catalyzing both the condensation of fatty acids and amino acids to generate N-acyl amino acids and also the reverse hydrolytic reaction.
GO:0046872 metal ion binding	IEA GO_REF:0000043	KEEP AS NON CORE	Summary: KEEP_AS_NON_CORE. PM20D1 is a zinc metalloenzyme that binds metal ions for catalytic activity. The catalytic activity depends on conserved histidine and aspartate residues (H125, D127, H465) predicted to coordinate divalent cations in the active site, which is typical of M20 metallopeptidases. While accurate, this is ancillary to the core N-acyl amino acid synthase/hydrolase function. Reason: Accurate but ancillary to the core catalytic function Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-cyberian.md The catalytic activity of PM20D1 depends on conserved residues characteristic of the M20 metallopeptidase family. The histidine and aspartate residues (H125, D127, H465) are predicted to coordinate a metal ion, likely zinc, in the active site.
GO:1990845 adaptive thermogenesis	TAS Reactome:R-HSA-9673053	ACCEPT	Summary: ACCEPT. PM20D1 synthesizes N-acyl amino acids that function as UCP1-independent mitochondrial uncouplers, directly contributing to adaptive thermogenesis. This is supported by experimental evidence that PM20D1 overexpression increases energy expenditure and that N-acyl amino acids increase thermogenesis. Supporting Evidence: PMID:27374330 N-acyl amino acids directly bind mitochondria and function as endogenous uncouplers of UCP1-independent respiration.
GO:1990845 adaptive thermogenesis	TAS Reactome:R-HSA-9673054	ACCEPT	Summary: ACCEPT. Same GO term from different Reactome pathway entry. Both the synthase and hydrolase reactions contribute to regulating N-acyl amino acid levels for thermogenesis. PM20D1 is highly expressed in brown adipose tissue and is cold-inducible. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-falcon.md Endogenous secretion from brown adipose tissue (BAT), liver, kidney, and intestine has been detected; adipocytes secrete PM20D1 into circulation.
GO:1990845 adaptive thermogenesis	IBA GO_REF:0000033	ACCEPT	Summary: ACCEPT. Phylogenetic inference supporting the role in adaptive thermogenesis, consistent with TAS evidence. The N-acyl amino acid products represent a UCP1-independent thermogenic pathway that has evolved in mammals. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-perplexity.md PM20D1 appears to lack a direct yeast ortholog. The specialized function of PM20D1 in N-fatty acyl amino acid metabolism represents a mammalian-specific innovation potentially related to the evolution of thermogenic adipose tissue.
GO:1990845 adaptive thermogenesis	IEA GO_REF:0000120	ACCEPT	Summary: ACCEPT. Electronic annotation supporting the role in adaptive thermogenesis. Mice with elevated circulating PM20D1 demonstrate augmented oxygen consumption and reduced weight gain when fed a high-fat diet. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-cyberian.md Mice with elevated circulating PM20D1, achieved through adeno-associated viral vector delivery, demonstrate augmented oxygen consumption and reduced weight gain when fed a high-fat diet. These animals also have increased circulating N-acyl amino acids.
GO:0043604 obsolete amide biosynthetic process	IDA PMID:27374330 The Secreted Enzyme PM20D1 Regulates Lipidated Amino Acid Un...	ACCEPT	Summary: ACCEPT. PM20D1 catalyzes the biosynthesis of N-acyl amino acids (amides) from fatty acids and amino acids. This synthase activity is directly demonstrated in vitro. Supporting Evidence: PMID:27374330 We demonstrate that PM20D1 is a bidirectional enzyme in vitro, catalyzing both the condensation of fatty acids and amino acids to generate N-acyl amino acids and also the reverse hydrolytic reaction.
GO:0043604 obsolete amide biosynthetic process	IBA GO_REF:0000033	ACCEPT	Summary: ACCEPT. Phylogenetic inference consistent with experimental IDA evidence. The synthase reaction preferentially uses phenylalanine and oleate as substrates to generate N-oleoyl-phenylalanine, one of the key N-acyl amino acid products. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-cyberian.md For the synthase reaction, phenylalanine is the amino acid most efficiently converted to its corresponding N-acyl amino acid product when incubated with oleate. PM20D1 can also condense other amino acids with oleate, although less efficiently than phenylalanine.
GO:0043604 obsolete amide biosynthetic process	IEA GO_REF:0000120	ACCEPT	Summary: ACCEPT. Electronic annotation consistent with experimental IDA evidence. The synthase activity generates N-acyl amino acids that function as endogenous mitochondrial uncouplers. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-falcon.md Under assay conditions, PM20D1 exhibited markedly higher hydrolase conversion (~94%) than synthase conversion (~1.2%), highlighting strong hydrolase activity and more selective synthetic activity.
GO:0043605 obsolete amide catabolic process	IDA PMID:27374330 The Secreted Enzyme PM20D1 Regulates Lipidated Amino Acid Un...	ACCEPT	Summary: ACCEPT. PM20D1 catalyzes the hydrolysis (catabolism) of N-acyl amino acids, the reverse of the synthase reaction. This is directly demonstrated in vitro. Supporting Evidence: PMID:27374330 We demonstrate that PM20D1 is a bidirectional enzyme in vitro, catalyzing both the condensation of fatty acids and amino acids to generate N-acyl amino acids and also the reverse hydrolytic reaction.
GO:0043605 obsolete amide catabolic process	IBA GO_REF:0000033	ACCEPT	Summary: ACCEPT. Phylogenetic inference consistent with experimental IDA evidence. The hydrolase activity is more promiscuous than synthase activity, efficiently cleaving all N-oleoyl amino acids tested. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-cyberian.md The hydrolase activity of PM20D1 appears to be more promiscuous than the synthase activity. PM20D1 efficiently hydrolyzes all N-oleoyl amino acids tested, including those with amino acids that are poorly utilized as synthase substrates.
GO:0043605 obsolete amide catabolic process	IEA GO_REF:0000120	ACCEPT	Summary: ACCEPT. Electronic annotation consistent with experimental IDA evidence. PM20D1 exhibits robust hydrolase activity (~94% conversion under assay conditions). Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-falcon.md Under assay conditions, PM20D1 exhibited markedly higher hydrolase conversion (~94%) than synthase conversion (~1.2%), highlighting strong hydrolase activity and more selective synthetic activity.
GO:0006629 lipid metabolic process	IDA PMID:27374330 The Secreted Enzyme PM20D1 Regulates Lipidated Amino Acid Un...	KEEP AS NON CORE	Summary: KEEP_AS_NON_CORE. PM20D1 uses fatty acids as substrates for N-acyl amino acid synthesis. This is correct but general - the more specific involvement is in N-acyl amino acid metabolism which are lipid-amino acid conjugates. Reason: Accurate but general; the specific pathway is N-acyl amino acid metabolism Supporting Evidence: PMID:27374330 Jun 30. The Secreted Enzyme PM20D1 Regulates Lipidated Amino Acid Uncouplers of Mitochondria.
GO:0006629 lipid metabolic process	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: KEEP_AS_NON_CORE. Consistent with IDA evidence. Accurate but general term. Reason: Accurate but general; the specific pathway is N-acyl amino acid metabolism
GO:0006629 lipid metabolic process	IEA GO_REF:0000120	KEEP AS NON CORE	Summary: KEEP_AS_NON_CORE. Consistent with IDA evidence. Accurate but general term. Reason: Accurate but general; the specific pathway is N-acyl amino acid metabolism
GO:0006520 amino acid metabolic process	IDA PMID:27374330 The Secreted Enzyme PM20D1 Regulates Lipidated Amino Acid Un...	KEEP AS NON CORE	Summary: KEEP_AS_NON_CORE. PM20D1 uses amino acids (preferentially phenylalanine) as substrates for N-acyl amino acid synthesis. Correct but general. Reason: Accurate but general; the specific pathway is N-acyl amino acid metabolism Supporting Evidence: PMID:27374330 Jun 30. The Secreted Enzyme PM20D1 Regulates Lipidated Amino Acid Uncouplers of Mitochondria.
GO:0006520 amino acid metabolic process	IEA GO_REF:0000120	KEEP AS NON CORE	Summary: KEEP_AS_NON_CORE. Consistent with IDA evidence. Accurate but general term. Reason: Accurate but general; the specific pathway is N-acyl amino acid metabolism
GO:0006631 fatty acid metabolic process	IEA GO_REF:0000041	KEEP AS NON CORE	Summary: KEEP_AS_NON_CORE. PM20D1 uses fatty acids as substrates for N-acyl amino acid synthesis/hydrolysis. Correct but indirect - PM20D1 conjugates fatty acids to amino acids rather than catabolizing or synthesizing fatty acids per se. Reason: Fatty acids are substrates, but PM20D1 doesn't catabolize or synthesize them
GO:0097009 energy homeostasis	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: KEEP_AS_NON_CORE. PM20D1 contributes to energy homeostasis through production of N-acyl amino acid uncouplers. This is a downstream physiological effect rather than the direct enzymatic function. PM20D1-knockout mice exhibit insulin resistance and impaired glucose tolerance, while overexpression improves metabolic parameters. Reason: Downstream physiological effect, not direct enzymatic function Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-cyberian.md Global genetic ablation of PM20D1 in mice results in metabolic dysfunction. PM20D1-knockout mice exhibit insulin resistance, altered body temperature following cold exposure, and impaired glucose tolerance.
GO:0006508 proteolysis	IEA GO_REF:0000043	REMOVE	Summary: REMOVE. PM20D1 does not perform proteolysis. Despite its classification in the M20 peptidase family, PM20D1 has completely abandoned its ancestral peptide-cleaving function through neofunctionalization. It hydrolyzes N-acyl amino acids (fatty acid-amino acid conjugates), not peptide bonds in proteins. This represents one of the most striking examples of enzymatic neofunctionalization in evolution. Reason: Incorrect. PM20D1 does not cleave peptide bonds or perform proteolysis. Its substrate is N-acyl amino acids, not proteins or peptides. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-cyberian.md Despite belonging to the 2.5-billion-year-old M20 metallopeptidase family, PM20D1 has completely abandoned its ancestral peptide-cleaving function. file:human/PM20D1/PM20D1-deep-research-perplexity.md PM20D1 has completely abandoned its ancestral peptide-cleaving function. Instead, it evolved into a bidirectional enzyme that synthesizes and hydrolyzes N-acyl amino acids.
GO:0005576 extracellular region	TAS Reactome:R-HSA-9673053	ACCEPT	Summary: ACCEPT. PM20D1 is a secreted enzyme that functions in the extracellular space. It has a classical signal peptide and is found in circulation associated with lipoproteins. Supporting Evidence: PMID:27374330 Mice with increased circulating PM20D1 have augmented respiration and increased N-acyl amino acids in blood.
GO:0005576 extracellular region	TAS Reactome:R-HSA-9673054	ACCEPT	Summary: ACCEPT. PM20D1 is secreted and circulates in tight association with LDL and HDL lipoprotein particles, which function as co-activators of its enzymatic activity. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-cyberian.md PM20D1 does not circulate as a free enzyme but rather associates with lipoprotein particles. The tight association with both LDL and HDL positions PM20D1 in a lipid-rich microenvironment that facilitates access to fatty acid substrates and enhances its enzymatic activity.
GO:0005576 extracellular region	IEA GO_REF:0000120	ACCEPT	Summary: ACCEPT. Electronic annotation consistent with TAS evidence. PM20D1 contains an N-terminal signal peptide that directs it to the secretory pathway. The bioavailability of its N-acyl amino acid products in circulation is regulated by interaction with serum albumin. Supporting Evidence: file:human/PM20D1/PM20D1-deep-research-cyberian.md The bioavailability of N-acyl amino acids in circulation is regulated by their interaction with serum albumin. Approximately 96.5% of total plasma N-acyl amino acids are bound to protein, primarily albumin.
GO:0005615 extracellular space	IEA GO_REF:0000107	ACCEPT	Summary: ACCEPT. PM20D1 is secreted into the extracellular space and circulates in blood associated with lipoprotein particles. Supporting Evidence: PMID:27374330 Mice with increased circulating PM20D1 have augmented respiration and increased N-acyl amino acids in blood.
GO:0070062 extracellular exosome	HDA PMID:19056867 Large-scale proteomics and phosphoproteomics of urinary exos...	KEEP AS NON CORE	Summary: KEEP_AS_NON_CORE. PM20D1 was detected in urinary exosomes by high-throughput proteomics (HDA evidence). This represents a location where PM20D1 can be found, but its primary functional location is the extracellular space/blood associated with LDL and HDL lipoprotein particles, which serve as co-activators of its enzymatic activity. Reason: High-throughput detection; primary location is extracellular space with lipoproteins Supporting Evidence: PMID:19056867 the analysis identified 1132 proteins unambiguously file:human/PM20D1/PM20D1-deep-research-cyberian.md PM20D1 does not circulate as a free enzyme but rather associates with lipoprotein particles. The tight association with both LDL and HDL positions PM20D1 in a lipid-rich microenvironment that facilitates access to fatty acid substrates and enhances its enzymatic activity.

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