HSD17B4

UniProt ID: P51659
Organism: Homo sapiens
Review Status: INITIALIZED
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Gene Description

HSD17B4 encodes the peroxisomal multifunctional enzyme type 2 (MFE-2/MFP-2), also known as D-bifunctional protein (DBP), a 736-residue enzyme of the peroxisomal matrix that catalyzes the second (hydration) and third (dehydrogenation) reactions of peroxisomal fatty-acid beta-oxidation with D (R) stereochemistry. It is a multidomain protein: an N-terminal (3R)-hydroxyacyl-CoA dehydrogenase domain of the short-chain dehydrogenase/reductase (SDR) family with an NAD(+)-binding Rossmann fold (historically named 17-beta-hydroxysteroid dehydrogenase type 4), a central D-specific enoyl-CoA hydratase 2 / (3R)-3-hydroxyacyl-CoA dehydratase domain of the MaoC/hot-dog fold, and a C-terminal SCP2-like sterol-carrier / lipid-transfer domain. The full-length protein is bifunctional and forms homodimers; in vivo it is proteolytically processed into separate dehydrogenase and hydratase chains. DBP is the main bifunctional enzyme handling very-long-chain fatty acids, 2-methyl-branched-chain (pristanic) acids, C27 bile-acid intermediates (di- and trihydroxycholestanoic acid), and long-chain dicarboxylic acids, and it participates in the peroxisomal beta-oxidation step that retroconverts C24:6n-3 to docosahexaenoic acid (DHA). Its 3-oxoacyl-CoA product is passed to the peroxisomal thiolase step (SCPx/ACAA1). Loss of function causes D-bifunctional protein deficiency, a severe Zellweger-like neonatal peroxisomal disorder, while milder hypomorphic alleles cause Perrault syndrome (sensorineural deafness with ovarian dysgenesis).

Existing Annotations Review

GO Term Evidence Action Reason
GO:0106386 (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
IBA
GO_REF:0000033
ACCEPT
Summary: Phylogenetically-inferred (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity, the N-terminal dehydrogenase catalytic activity of DBP. This is one of the two core enzymatic functions and is directly supported by biochemistry (see IDA annotations to the same term).
Supporting Evidence:
file:human/HSD17B4/HSD17B4-uniprot.txt
a (3R)-3-hydroxyacyl-CoA + NAD(+) = a 3-oxoacyl-CoA + NADH +
GO:0005777 peroxisome
IBA
GO_REF:0000033
ACCEPT
Summary: Phylogenetically-inferred peroxisomal localization; correct. DBP is a peroxisomal-matrix enzyme with a C-terminal PTS1-like targeting motif, consistent with IDA immunofluorescence.
Supporting Evidence:
file:human/HSD17B4/HSD17B4-uniprot.txt
SUBCELLULAR LOCATION: Peroxisome
GO:0006635 fatty acid beta-oxidation
IBA
GO_REF:0000033
ACCEPT
Summary: Phylogenetically-inferred involvement in fatty acid beta-oxidation, the core biological process for DBP (it catalyzes reactions 2 and 3 of the peroxisomal beta-oxidation cycle).
Supporting Evidence:
file:human/HSD17B4/HSD17B4-uniprot.txt
Bifunctional enzyme acting on the peroxisomal fatty acid
GO:0005777 peroxisome
IEA
GO_REF:0000120
ACCEPT
Summary: Electronic peroxisome localization (UniProt subcellular-location/ARBA). Correct and redundant with the experimentally-supported peroxisome/peroxisomal-matrix annotations.
GO:0006629 lipid metabolic process
IEA
GO_REF:0000117
MARK AS OVER ANNOTATED
Summary: Electronic ARBA annotation to the very general parent term 'lipid metabolic process'. Not wrong but far less informative than fatty acid beta-oxidation; a high-level grouping term.
GO:0016616 oxidoreductase activity, acting on the CH-OH group of donors, NAD or NADP as acceptor
IEA
GO_REF:0000117
MODIFY
Summary: Electronic ARBA annotation to a broad oxidoreductase grouping term. This is a correct but non-specific ancestor of the actual (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity; the specific term GO:0106386 should be used instead.
GO:0018812 3-hydroxyacyl-CoA dehydratase activity
IEA
GO_REF:0000120
MODIFY
Summary: Electronic annotation to the dehydratase activity of the central hydratase-2 domain. Correct in essence; the D-specific term GO:0080023 ((2E)-enoyl-CoA hydratase activity, i.e. (3R)-3-hydroxyacyl-CoA = (2E)-enoyl-CoA + H2O) is the stereochemistry-precise term.
GO:0033989 3alpha,7alpha,12alpha-trihydroxy-5beta-cholest-24-enoyl-CoA hydratase activity
IEA
GO_REF:0000120
KEEP AS NON CORE
Summary: Electronic Rhea/EC-based annotation for the bile-acid (THCA-CoA) hydratase reaction (EC 4.2.1.107), a substrate-specific instance of DBP's hydratase-2 activity. This is a genuine, experimentally-supported substrate (di/trihydroxycholestanoic acid) so the term is retained as a substrate-specific non-core activity of the central hydratase domain.
Supporting Evidence:
file:human/HSD17B4/HSD17B4-uniprot.txt
EC=4.2.1.107
GO:0080023 (2E)-enoyl-CoA hydratase activity
IEA
GO_REF:0000120
ACCEPT
Summary: Electronic Rhea-based annotation to the D-specific (2E)-enoyl-CoA hydratase activity (EC 4.2.1.119); reaction (3R)-3-hydroxyacyl-CoA = (2E)-enoyl-CoA + H2O. This is the precise term for DBP's central hydratase-2 catalytic activity and is one of the two core functions.
Supporting Evidence:
file:human/HSD17B4/HSD17B4-uniprot.txt
EC=4.2.1.119
GO:0102158 very-long-chain (3R)-3-hydroxyacyl-CoA dehydratase activity
IEA
GO_REF:0000116
KEEP AS NON CORE
Summary: Electronic Rhea-based annotation to the VLCFA-specific instance of DBP's D-hydratase activity. Consistent with DBP being the main hydratase for very-long-chain fatty acids; a substrate-specific child of the core hydratase-2 activity.
Supporting Evidence:
file:human/HSD17B4/HSD17B4-uniprot.txt
a very-long-chain (3R)-3-hydroxyacyl-CoA = a very-long-chain
GO:0106386 (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
IEA
GO_REF:0000116
ACCEPT
Summary: Electronic Rhea-based annotation to the core dehydrogenase activity. Correct and redundant with the IDA/IBA annotations to the same term.
Supporting Evidence:
file:human/HSD17B4/HSD17B4-uniprot.txt
a (3R)-3-hydroxyacyl-CoA + NAD(+) = a 3-oxoacyl-CoA + NADH +
GO:0006635 fatty acid beta-oxidation
IEA
GO_REF:0000041
ACCEPT
Summary: Electronic UniPathway-based annotation to fatty acid beta-oxidation, the core process. Correct and redundant with the IDA/IBA evidence.
Supporting Evidence:
file:human/HSD17B4/HSD17B4-uniprot.txt
PATHWAY: Lipid metabolism; fatty acid beta-oxidation.
GO:0005777 peroxisome
IDA
GO_REF:0000052
ACCEPT
Summary: Immunofluorescence (HPA) peroxisome localization. Directly supports the core peroxisomal localization of DBP.
GO:0106386 (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
IDA
PMID:10706581
Peroxisomal fatty acid oxidation disorders and 58 kDa sterol...
ACCEPT
Summary: Direct assay evidence for the (3R)-3-hydroxyacyl-CoA dehydrogenase activity, measured via recombinant human D-bifunctional protein used to generate the bile-acid dehydrogenation product. Core catalytic activity.
Supporting Evidence:
PMID:10706581
expressing human D-bifunctional protein
GO:0106386 (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
IDA
PMID:15060085
Identification of the peroxisomal beta-oxidation enzymes inv...
ACCEPT
Summary: Direct enzyme-activity measurement of recombinant human DBP dehydrogenase on long-chain and dicarboxylic acyl-CoA substrates. Core catalytic activity.
Supporting Evidence:
PMID:15060085
direct enzyme measurements with human recombinant
GO:0106386 (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
IDA
PMID:9089413
Structure of D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl...
ACCEPT
Summary: Direct biochemical characterization of the purified/recombinant human bifunctional protein showing dehydrogenase activity; the full-length cDNA product has both dehydratase and dehydrogenase activities. Core catalytic activity, with defined kinetics.
Supporting Evidence:
PMID:9089413
exhibited both the dehydratase and dehydrogenase activities
GO:0106386 (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
IDA
PMID:9482850
Peroxisomal D-hydroxyacyl-CoA dehydrogenase deficiency: reso...
ACCEPT
Summary: Direct evidence that the D-bifunctional protein has 3-hydroxyacyl-CoA dehydrogenase activity, and expression of the Gly16Ser variant showed loss of this activity, confirming the dehydrogenase domain. Core catalytic activity.
Supporting Evidence:
PMID:9482850
enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase activity
GO:0106386 (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
IMP
PMID:9482850
Peroxisomal D-hydroxyacyl-CoA dehydrogenase deficiency: reso...
ACCEPT
Summary: Mutant-phenotype evidence (Gly16Ser in the NAD+-binding loop) abolishing the dehydrogenase activity, on the processed dehydrogenase chain (PRO_0000400082). Confirms the N-terminal dehydrogenase catalytic activity is required and mapped to this domain.
Supporting Evidence:
PMID:9482850
the G46A mutation causes the loss of the 3-hydroxyacyl-CoA dehydrogenase activity
GO:0004303 estradiol 17-beta-dehydrogenase [NAD(P)+] activity
IDA
PMID:7487879
Molecular cloning of a novel widely expressed human 80 kDa 1...
MARK AS OVER ANNOTATED
Summary: From the original cloning paper, which reported a unidirectional oxidative 17-beta-HSD (estradiol dehydrogenase) activity when the enzyme was over-expressed in mammalian cells. This is the historical basis of the 17-beta-HSD type 4 name, but the physiological substrates are fatty-acyl-CoAs, not steroids; UniProt's FUNCTION section describes only fatty-acid/bile-acid metabolism. This steroid activity is an in-vitro side reaction and an over-annotation of the enzyme's core evolved role. Retained (experimental IDA) but flagged.
Supporting Evidence:
PMID:7487879
17 beta-HSD IV enzyme displays a specific unidirectional oxidative 17 beta-HSD activity
GO:0004300 enoyl-CoA hydratase activity
IDA
PMID:10706581
Peroxisomal fatty acid oxidation disorders and 58 kDa sterol...
MODIFY
Summary: Direct evidence for enoyl-CoA hydratase activity (the enoyl-CoA of the bile-acid intermediate THCA is hydrated by recombinant human DBP). Correct; this is the parent of the D-specific hydratase-2 activity. MODIFY to the stereochemistry-precise term GO:0080023.
Supporting Evidence:
PMID:10706581
preincubating the enoyl-CoA of the bile acid intermediate THCA
GO:0004300 enoyl-CoA hydratase activity
IDA
PMID:15060085
Identification of the peroxisomal beta-oxidation enzymes inv...
MODIFY
Summary: Direct enzyme-activity measurement of the DBP hydratase on long-chain / dicarboxylic substrates. Correct but non-specific; MODIFY to the D-specific hydratase-2 term GO:0080023.
Supporting Evidence:
PMID:15060085
direct enzyme measurements with human recombinant
GO:0004300 enoyl-CoA hydratase activity
IDA
PMID:9482850
Peroxisomal D-hydroxyacyl-CoA dehydrogenase deficiency: reso...
MODIFY
Summary: Direct evidence that DBP has enoyl-CoA hydratase activity; the enoyl-CoA hydratase activity was normal in a patient with an isolated dehydrogenase defect, confirming the distinct hydratase function. MODIFY to the D-specific term GO:0080023.
Supporting Evidence:
PMID:9482850
the enoyl-CoA hydratase activity of d -bifunctional protein was normal
GO:0006635 fatty acid beta-oxidation
IDA
PMID:10706581
Peroxisomal fatty acid oxidation disorders and 58 kDa sterol...
ACCEPT
Summary: Direct evidence connecting DBP to peroxisomal beta-oxidation of bile-acid intermediates. Core biological process.
Supporting Evidence:
PMID:10706581
peroxisomal oxidation of branched-chain fatty acids
GO:0006635 fatty acid beta-oxidation
IDA
PMID:15060085
Identification of the peroxisomal beta-oxidation enzymes inv...
ACCEPT
Summary: Direct evidence that DBP is one of the main enzymes in peroxisomal beta-oxidation of long-chain dicarboxylic acids. Core biological process.
Supporting Evidence:
PMID:15060085
the main enzymes involved in beta-oxidation of C16DCA are SCOX, both LBP and DBP
GO:0006635 fatty acid beta-oxidation
IDA
PMID:9482850
Peroxisomal D-hydroxyacyl-CoA dehydrogenase deficiency: reso...
ACCEPT
Summary: Direct evidence that DBP plays an essential, non-redundant role in the peroxisomal beta-oxidation pathway. Core biological process.
Supporting Evidence:
PMID:9482850
plays an essential role in the peroxisomal Ξ²-oxidation pathway
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-192331
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix in the context of the bile-acid (THCA-CoA hydration) reaction. Correct and the most precise localization term; the peroxisomal matrix is the functional compartment for DBP catalysis.
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-193455
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix (bile-acid intermediate dehydrogenation reaction). Correct core localization.
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-193508
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix (bile-acid intermediate reaction). Correct core localization.
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-193535
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix (bile-acid intermediate hydration reaction). Correct core localization.
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-2066778
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix (hydration step in DHA-synthesis beta-oxidation). Correct core localization.
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-2066780
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix (dehydrogenation step in DHA-synthesis beta-oxidation). Correct core localization.
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-389986
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix (pristanoyl-CoA hydration step). Correct core localization.
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-389995
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix (pristanoyl-CoA dehydrogenation step). Correct core localization.
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-390251
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix (VLCFA 3-hydroxyacyl-CoA dehydrogenation step). Correct core localization.
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-390252
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix (VLCFA enoyl-CoA hydration step). Correct core localization.
GO:0005782 peroxisomal matrix
TAS
Reactome:R-HSA-9033235
ACCEPT
Summary: Reactome TAS localizing DBP to the peroxisomal matrix as PEX5 import cargo (translocation from cytosol to matrix). Correct destination compartment for the imported enzyme.
GO:0005829 cytosol
TAS
Reactome:R-HSA-9033235
KEEP AS NON CORE
Summary: Reactome TAS placing DBP in the cytosol as newly-synthesized PTS1 cargo before import. This reflects the transient import route, not the functional compartment; DBP acts in the peroxisomal matrix. Non-core.
GO:0005829 cytosol
TAS
Reactome:R-HSA-9033236
KEEP AS NON CORE
Summary: Reactome TAS placing DBP in the cytosol as PEX5 cargo binding the docking/translocation module. Import-route intermediate, not the functional compartment. Non-core.
GO:0001649 osteoblast differentiation
HDA
PMID:16210410
Differential expression profiling of membrane proteins by qu...
MARK AS OVER ANNOTATED
Summary: High-throughput proteomics screen of membrane-protein expression changes in a mesenchymal stem cell line undergoing osteoblast differentiation. DBP was detected as a differentially expressed protein, not shown to have any functional role in differentiation. An expression correlation, not a functional involvement; over-annotation.
Supporting Evidence:
PMID:16210410
changes in expression of membrane protein markers
GO:0016020 membrane
HDA
PMID:16210410
Differential expression profiling of membrane proteins by qu...
MARK AS OVER ANNOTATED
Summary: From a membrane-protein proteomics screen; DBP co-fractionated in a membrane-enriched preparation. DBP is a soluble peroxisomal-matrix enzyme, not an integral membrane protein; this is a co-fractionation artifact / over-annotation of location.
Supporting Evidence:
PMID:16210410
expression profiling of membrane proteins by quantitative
GO:0005777 peroxisome
IDA
PMID:15599942
Peroxisomal branched chain fatty acid beta-oxidation pathway...
ACCEPT
Summary: Direct evidence (branched-chain fatty-acid beta-oxidation study in prostate) supporting peroxisomal localization and activity of DBP. Correct core localization.
Supporting Evidence:
PMID:15599942
D-bifunctional protein (DBP)-is also upregulated in prostate cancer
GO:0042803 protein homodimerization activity
IDA
PMID:15644212
Crystal structure of 2-enoyl-CoA hydratase 2 from human pero...
KEEP AS NON CORE
Summary: Crystal structure of the human MFE-2 hydratase-2 domain, which forms a hot-dog-fold dimer; the full-length enzyme is a homodimer. Homodimerization is a real structural property but is a supporting feature of the active enzyme rather than a distinct core molecular function; retained as non-core.
Supporting Evidence:
PMID:15644212
having a two-domain subunit structure
GO:0018812 3-hydroxyacyl-CoA dehydratase activity
IDA
PMID:9482850
Peroxisomal D-hydroxyacyl-CoA dehydrogenase deficiency: reso...
MODIFY
Summary: Direct evidence for the D-hydroxyacyl-CoA dehydratase / enoyl-CoA hydratase activity of DBP (normal hydratase activity in a dehydrogenase-defect patient). Correct; MODIFY to the stereochemistry-precise D term GO:0080023.
Supporting Evidence:
PMID:9482850
the enoyl-CoA hydratase activity of d -bifunctional protein was normal
GO:0005777 peroxisome
NAS
PMID:9482850
Peroxisomal D-hydroxyacyl-CoA dehydrogenase deficiency: reso...
ACCEPT
Summary: Non-traceable author statement that DBP is a peroxisomal beta-oxidation enzyme. Correct core localization, supported more strongly by IDA/TAS annotations.
Supporting Evidence:
PMID:9482850
a new peroxisomal Ξ²-oxidation enzyme was recently described
GO:0036111 very long-chain fatty-acyl-CoA metabolic process
IDA
PMID:9482850
Peroxisomal D-hydroxyacyl-CoA dehydrogenase deficiency: reso...
KEEP AS NON CORE
Summary: Direct evidence that DBP is involved in VLCFA metabolism: DBP-deficient patients accumulate straight-chain very-long-chain fatty acids, and DBP may be the main VLCFA beta-oxidation enzyme. A biologically important substrate class; keep, though it is a specialization of the core fatty acid beta-oxidation process.
Supporting Evidence:
PMID:9482850
accumulates straight-chain fatty acids (VLCFA) both in plasma and fibroblasts
GO:0018812 3-hydroxyacyl-CoA dehydratase activity
IDA
PMID:9089413
Structure of D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl...
MODIFY
Summary: Direct biochemical evidence: the purified human bifunctional protein has dehydratase activity, and a truncated C-terminal fragment retains only dehydratase activity, mapping it to the hydratase-2 domain. Correct; MODIFY to the D-specific term GO:0080023.
Supporting Evidence:
PMID:9089413
exhibited only the dehydratase activity
GO:0036112 medium-chain fatty-acyl-CoA metabolic process
IDA
PMID:9089413
Structure of D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl...
KEEP AS NON CORE
Summary: Direct evidence from kinetic characterization on medium-chain substrates (e.g. D-3-hydroxy- octanoyl-CoA, decanoyl-CoA). A substrate-specific specialization of DBP's beta-oxidation activity; retained as non-core.
Supporting Evidence:
file:human/HSD17B4/HSD17B4-uniprot.txt
KM=10 uM for D-3-hydroxy-octanoyl-CoA
GO:0042803 protein homodimerization activity
IDA
PMID:9089413
Structure of D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl...
KEEP AS NON CORE
Summary: Direct evidence that the native enzyme is a homodimer (of the 77-kDa polypeptide). Structural property supporting the active enzyme; retained as non-core.
Supporting Evidence:
PMID:9089413
the native enzyme is a homodimer of 77-kDa
GO:0005778 peroxisomal membrane
HDA
PMID:21525035
PEX14 is required for microtubule-based peroxisome motility ...
MARK AS OVER ANNOTATED
Summary: HDA localization to the peroxisomal membrane, from a proteomics study whose subject is PEX14 and microtubule-based peroxisome motility (DBP is not its focus). DBP is a soluble matrix enzyme; membrane co-purification reflects peroxisome-membrane proteome preparation, not integral membrane localization. Over-annotation of location.
Supporting Evidence:
PMID:21525035
isolating native peroxisomal membrane protein complexes from cultured human cells
GO:0006635 fatty acid beta-oxidation
IDA
PMID:10400999
Enoyl-CoA hydratase deficiency: identification of a new type...
ACCEPT
Summary: Direct evidence: DBP is involved in peroxisomal beta-oxidation of VLCFAs, branched-chain fatty acids and bile-acid intermediates; a new hydratase-domain deficiency was defined here. Core biological process.
Supporting Evidence:
PMID:10400999
D-bifunctional protein is involved in the peroxisomal beta-oxidation of very long chain fatty acids, branched chain fatty acids and bile acid intermediates
GO:0018812 3-hydroxyacyl-CoA dehydratase activity
IDA
PMID:10400999
Enoyl-CoA hydratase deficiency: identification of a new type...
MODIFY
Summary: Direct evidence for the enoyl-CoA hydratase (dehydratase) domain activity; two patients had an isolated defect in the enoyl-CoA hydratase domain of DBP (Asn457Tyr). Correct; MODIFY to the D-specific term GO:0080023.
Supporting Evidence:
PMID:10400999
an isolated defect in the enoyl-CoA hydratase domain of D-bifunctional protein
GO:0005777 peroxisome
NAS
PMID:7487879
Molecular cloning of a novel widely expressed human 80 kDa 1...
ACCEPT
Summary: Non-traceable author statement of peroxisomal localization from the original cloning paper (the C-terminal region is similar to sterol carrier protein 2, a peroxisomal marker). Correct core localization, supported more strongly by IDA/TAS annotations.
Supporting Evidence:
PMID:7487879
amino acids 596-736 which are similar to human sterol
GO:0008209 androgen metabolic process
IDA
PMID:7487879
Molecular cloning of a novel widely expressed human 80 kDa 1...
MARK AS OVER ANNOTATED
Summary: From the original cloning paper reporting 17-beta-HSD (steroid) activity in over-expressing cells. DBP's physiological substrates are fatty-acyl-CoAs, not androgens; UniProt's FUNCTION section describes only fatty-acid/bile-acid metabolism. This steroid-metabolism process is a side reaction and an over-annotation of the enzyme's core role. Retained (experimental IDA) but flagged.
Supporting Evidence:
PMID:7487879
Reactions of oestrogens and androgens at position C-17 are catalysed by 17 beta-hydroxysteroid dehydrogenases
GO:0008210 estrogen metabolic process
IDA
PMID:7487879
Molecular cloning of a novel widely expressed human 80 kDa 1...
MARK AS OVER ANNOTATED
Summary: From the original cloning paper reporting oxidative 17-beta-estradiol dehydrogenase activity in over-expressing cells. As with androgen metabolism, this is an in-vitro steroid side activity, not the enzyme's physiological (fatty-acid) role; over-annotation. Retained (experimental IDA) but flagged.
Supporting Evidence:
PMID:7487879
17 beta-HSD IV enzyme displays a specific unidirectional oxidative 17 beta-HSD activity

Core Functions

D-specific enoyl-CoA hydratase 2 (D-3-hydroxyacyl-CoA dehydratase) activity: the central MaoC/hot-dog-fold domain hydrates a (2E)-enoyl-CoA to a (3R)-3-hydroxyacyl-CoA (EC 4.2.1.119), the second reaction of each peroxisomal beta-oxidation cycle, acting on very-long-chain, 2-methyl-branched (pristanic) and bile-acid-intermediate acyl-CoAs in the peroxisomal matrix.

Directly Involved In:
Cellular Locations:
Supporting Evidence:
  • file:human/HSD17B4/HSD17B4-uniprot.txt
    hydration of 2-enoyl-CoA (trans-2-enoyl-CoA) to
  • PMID:9089413
    exhibited only the dehydratase activity

(3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity: the N-terminal SDR/Rossmann-fold domain oxidizes a (3R)-3-hydroxyacyl-CoA with NAD+ to a 3-oxoacyl-CoA (EC 1.1.1.n12), the third reaction of each peroxisomal beta-oxidation cycle; the 3-oxoacyl-CoA product is handed to the peroxisomal thiolase step. Acts on the same VLCFA, branched-chain and bile-acid substrates.

Supporting Evidence:
  • file:human/HSD17B4/HSD17B4-uniprot.txt
    dehydrogenation of (3R)-3-
  • PMID:9482850
    enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase activity

References

Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniPathway vocabulary mapping
Gene Ontology annotation based on curation of immunofluorescence data
Automatic Gene Ontology annotation based on Rhea mapping
Electronic Gene Ontology annotations created by ARBA machine learning models
Combined Automated Annotation using Multiple IEA Methods
Enoyl-CoA hydratase deficiency: identification of a new type of D-bifunctional protein deficiency.
Peroxisomal fatty acid oxidation disorders and 58 kDa sterol carrier protein X (SCPx). Activity measurements in liver and fibroblasts using a newly developed method.
Identification of the peroxisomal beta-oxidation enzymes involved in the degradation of long-chain dicarboxylic acids.
Peroxisomal branched chain fatty acid beta-oxidation pathway is upregulated in prostate cancer.
Crystal structure of 2-enoyl-CoA hydratase 2 from human peroxisomal multifunctional enzyme type 2.
Differential expression profiling of membrane proteins by quantitative proteomics in a human mesenchymal stem cell line undergoing osteoblast differentiation.
PEX14 is required for microtubule-based peroxisome motility in human cells.
Molecular cloning of a novel widely expressed human 80 kDa 17 beta-hydroxysteroid dehydrogenase IV.
Structure of D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase bifunctional protein.
Peroxisomal D-hydroxyacyl-CoA dehydrogenase deficiency: resolution of the enzyme defect and its molecular basis in bifunctional protein deficiency.
Identification of the peroxisomal beta-oxidation enzymes involved in the biosynthesis of docosahexaenoic acid.
Reactome:R-HSA-192331
3alpha,7alpha,12alpha-trihydroxy-5beta-cholest-24-enoyl-CoA (THCA-CoA) is hydrated to (24R, 25R) 3alpha,7alpha,12alpha,24-tetrahydroxy-5beta-cholestanoyl-CoA
Reactome:R-HSA-193455
(24R, 25R) 3alpha,7alpha,12alpha,24-tetrahydroxy-5beta-cholestanoyl-CoA is oxidized to 3alpha,7alpha,12alpha-trihydroxy-5beta-cholest-24-one-CoA
Reactome:R-HSA-193508
(24R, 25R) 3alpha,7alpha,24-trihydroxy-5beta-cholestanoyl-CoA is oxidized to 3alpha,7alpha-dihydroxy-5beta-cholest-24-one-CoA
Reactome:R-HSA-193535
25(S) 3alpha,7alpha-dihydroxy-5beta-cholest-24-enoyl-CoA is hydrated to (24R, 25R) 3alpha,7alpha,24-trihydroxy-5beta-cholestanoyl-CoA
Reactome:R-HSA-2066778
Hydration of delta2-tetracosaheptaenoyl-CoA to 3-hydroxy tetracosahexaenoyl-CoA
Reactome:R-HSA-2066780
Dehydrogenation of 3-hydroxy tetracosahexaenoyl-CoA
Reactome:R-HSA-389986
trans-2,3-dehydropristanoyl-CoA + H2O => 3-hydroxypristanoyl-CoA
Reactome:R-HSA-389995
3-hydroxypristanoyl-CoA + NAD+ => 3-ketoxypristanoyl-CoA + NADH + H+
Reactome:R-HSA-390251
HSD17B4 dehydrogenates 3-hydroxyhexacosanoyl-CoA
Reactome:R-HSA-390252
HSD17B4 hydrates trans-2,3-dehydrohexacosanoyl-CoA
Reactome:R-HSA-9033235
Cargo of PEX5S,L translocates from the cytosol to the peroxisomal matrix
Reactome:R-HSA-9033236
PEX5S,L:Cargo binds PEX13:PEX14:PEX2:PEX10:PEX12 (Docking and Translocation Module)

Suggested Questions for Experts

Q: Given that DBP's physiological substrates are fatty-acyl-CoAs, should the historical 17-beta-hydroxysteroid dehydrogenase (estradiol/androgen/estrogen) activities be retained as curated functions, or reclassified as in-vitro side activities?

Q: Which peroxisomal beta-oxidation substrate classes (VLCFA vs pristanic/bile-acid vs dicarboxylic vs PUFA/DHA) depend most non-redundantly on DBP versus the L-bifunctional protein (EHHADH)?

Suggested Experiments

Experiment: Substrate-resolved metabolomics of DBP-null versus EHHADH-null cells to quantify the non-redundant contribution of DBP to each acyl-CoA class (VLCFA, pristanoyl, DHCA/THCA, C16DCA, C24:6n-3).

Experiment: Structure-guided mutagenesis of the hydratase-2 substrate-binding loops to test whether the reported steroid dehydrogenase activity and the fatty-acyl dehydrogenase activity can be separated, clarifying the physiological relevance of the 17-beta-HSD activity.

πŸ“š Additional Documentation

Notes

(HSD17B4-notes.md)

HSD17B4 (P51659) β€” review notes

Identity and overview

HSD17B4 encodes the peroxisomal multifunctional enzyme type 2 (MFE-2 / MFP-2), also
called D-bifunctional protein (DBP) and historically "17-beta-hydroxysteroid
dehydrogenase type 4 (17Ξ²-HSD4)". It is a 736-aa peroxisomal-matrix enzyme that catalyzes
steps 2 and 3 of peroxisomal fatty-acid beta-oxidation with D (R) stereochemistry.

The protein is multidomain (UniProt P51659 FT):
- N-terminal (3R)-hydroxyacyl-CoA dehydrogenase domain (aa 1–305; SDR/Rossmann fold, NAD+
binding), historically the "17Ξ²-HSD" part [file:human/HSD17B4/HSD17B4-uniprot.txt "REGION 1..305 /note=\"(3R)-hydroxyacyl-CoA dehydrogenase\""].
- Central enoyl-CoA hydratase 2 / D-3-hydroxyacyl-CoA dehydratase domain (aa 322–622;
MaoC-like hot-dog fold) [file:human/HSD17B4/HSD17B4-uniprot.txt "REGION 322..622 /note=\"Enoyl-CoA hydratase 2\""].
- C-terminal SCP2 sterol-carrier / lipid-transfer domain (aa 624–736)
[file:human/HSD17B4/HSD17B4-uniprot.txt "DOMAIN 624..736 /note=\"SCP2\""].

The mature protein carries a C-terminal peroxisomal targeting motif (aa 734–736, "AKL")
[file:human/HSD17B4/HSD17B4-uniprot.txt "MOTIF 734..736 /note=\"Microbody targeting signal\""] and is imported
into the peroxisomal matrix. In vivo it is processed by the peroxisomal protease TYSND1 into
separate dehydrogenase and hydratase chains (PRO_0000400082 aa 1–311, PRO_0000400083 aa
312–736), but the full-length protein is bifunctional PMID:9089413.

Two catalytic activities (the core function)

DBP performs the 2nd (hydration) and 3rd (dehydrogenation) reactions of each beta-oxidation
cycle, in D/R stereochemistry:

  1. Enoyl-CoA hydratase 2 / D-3-hydroxyacyl-CoA dehydratase (EC 4.2.1.119 for the general
    reaction; EC 4.2.1.107 for the THCA-CoA bile-acid substrate): (2E)-enoyl-CoA + H2O β‡Œ
    (3R)-3-hydroxyacyl-CoA. UniProt CATALYTIC ACTIVITY: "a (3R)-3-hydroxyacyl-CoA = a
    (2E)-enoyl-CoA + H2O; ... EC=4.2.1.119"
    [file:human/HSD17B4/HSD17B4-uniprot.txt "EC=4.2.1.119"].
  2. (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) (EC 1.1.1.n12): (3R)-3-hydroxyacyl-CoA +
    NAD+ β‡Œ 3-oxoacyl-CoA + NADH + H+. UniProt CATALYTIC ACTIVITY: "a (3R)-3-hydroxyacyl-CoA +
    NAD(+) = a 3-oxoacyl-CoA + NADH + H(+); ... EC=1.1.1.n12"
    [file:human/HSD17B4/HSD17B4-uniprot.txt "EC=1.1.1.n12"].

The 3-oxoacyl-CoA product is handed to the peroxisomal thiolase step (SCPx/ACAA1) to complete
the cycle. UniProt FUNCTION: "Catalyzes two of the four reactions in fatty acid degradation:
hydration of 2-enoyl-CoA (trans-2-enoyl-CoA) to produce (3R)-3-hydroxyacyl-CoA, and
dehydrogenation of (3R)-3-hydroxyacyl-CoA to produce 3-ketoacyl-CoA (3-oxoacyl-CoA), which is
further metabolized by SCPx." [file:human/HSD17B4/HSD17B4-uniprot.txt "Catalyzes two of the four reactions in fatty"].

The bifunctional purified enzyme has both activities; a proteolytic C-terminal fragment
retains only the dehydratase PMID:9089413.
Original cloning identified the cDNA as identical to 17Ξ²-HSD IV PMID:9089413.

Physiological substrates: fatty acids, not steroids

Although first characterized as a 17Ξ²-hydroxysteroid dehydrogenase (from a porcine
17Ξ²-estradiol dehydrogenase probe), DBP's physiological substrates are fatty acyl-CoAs,
not steroids. It is the main bifunctional enzyme for:
- Very-long-chain fatty acids (VLCFAs) β€” DBP deficiency accumulates straight-chain VLCFA
PMID:9482850;
the D enzyme is suspected to be the main VLCFA beta-oxidation enzyme PMID:9482850.
- 2-methyl-branched-chain (pristanic) acids and C27 bile-acid intermediates (DHCA/THCA)
PMID:9482850.
- Long-chain dicarboxylic acids β€” DBP is among the main beta-oxidation enzymes for C16DCA
PMID:15060085.
- DHA (C22:6n-3) biosynthesis β€” peroxisomal beta-oxidation of C24:6n-3 to C22:6n-3 needs DBP
PMID:11734571.

The 1995 cloning paper reports only a "specific unidirectional oxidative 17Ξ²-HSD activity"
when over-expressed PMID:7487879;
this is the source of the estradiol/androgen/estrogen-dehydrogenase annotations. Physiologically
these steroid activities are minor/secondary side reactions of the fatty-acid oxidoreductase;
UniProt's RecName is "Peroxisomal multifunctional enzyme type 2", and the FUNCTION section
describes only fatty-acid/bile-acid metabolism, not steroid metabolism. The steroid MF/BP
annotations (GO:0004303, GO:0008209, GO:0008210) are therefore over-annotations of the
enzyme's core evolved role, but they rest on an IDA experiment (PMID:7487879) and are not
removed per curation policy.

Localization

Peroxisome / peroxisomal matrix. UniProt: "SUBCELLULAR LOCATION: Peroxisome"
[file:human/HSD17B4/HSD17B4-uniprot.txt "SUBCELLULAR LOCATION: Peroxisome"]. Supported by IDA
immunofluorescence (PMID:15599942, HPA GO_REF:0000052), Reactome peroxisomal-matrix TAS, and
the C-terminal PTS1-like microbody targeting signal. Cytosol/membrane/peroxisomal-membrane
annotations reflect the import route (PTS1 cargo transits cytosol before import; Reactome
R-HSA-9033235/9033236 model the PEX5 import machinery) or proteomics co-fractionation, not the
functional site of catalysis.

Structure / subunit

Homodimer [file:human/HSD17B4/HSD17B4-uniprot.txt "SUBUNIT: Homodimer"]. Crystal structures
solved for each domain: SCP2-like domain (1IKT), hydratase 2 (1S9C), dehydrogenase+NAD (1ZBQ).
The hydratase-2 crystal structure shows a hot-dog-fold dimer able to accommodate bulky C26,
pristanic and DHCA/THCA CoA esters PMID:15644212.
Homodimerization annotations (GO:0042803) are IDA-supported (PMID:15644212, PMID:9089413).

Disease

  • D-bifunctional protein deficiency (DBPD; MIM 261515) β€” severe autosomal-recessive
    peroxisomal beta-oxidation disorder; Zellweger-like neonatal presentation. Caused by
    variants in either the dehydrogenase domain (e.g. Gly16Ser, abolishes dehydrogenase activity
    PMID:9482850) or the hydratase domain (e.g. Asn457Tyr, isolated hydratase deficiency,
    unstable protein PMID:10400999) [file:human/HSD17B4/HSD17B4-uniprot.txt "D-bifunctional protein deficiency (DBPD) [MIM:261515]"].
  • Perrault syndrome 1 (PRLTS1; MIM 233400) β€” a milder allelic phenotype: sensorineural
    deafness + ovarian dysgenesis (Tyr217Cys) [PMID:20673864 via UniProt]
    [file:human/HSD17B4/HSD17B4-uniprot.txt "Perrault syndrome 1 (PRLTS1) [MIM:233400]"].

Non-core / incidental annotations to flag

  • osteoblast differentiation (GO:0001649, HDA, PMID:16210410) β€” from a proteomics
    differential-expression screen in a mesenchymal-stem-cell osteoblast model; DBP not even
    mentioned in the abstract. Expression change, not a functional role. Non-core.
  • membrane (GO:0016020) / peroxisomal membrane (GO:0005778) β€” HDA proteomics
    co-fractionation; DBP is a matrix enzyme, not an integral membrane protein. Over-annotated
    location.
  • cytosol (GO:0005829, TAS Reactome) β€” reflects the PTS1 import route, not the functional
    compartment.
  • PMID:21525035 (PEX14 microtubule motility) β€” about PEX14, not HSD17B4; the
    HSD17B4β†’peroxisomal-membrane HDA links to a proteomics dataset in that paper. Location
    over-annotation.

Core functions (for review)

Two catalytic MFs constitute the core evolved function:
1. GO:0080023 (2E)-enoyl-CoA hydratase activity β€” definition "a (3R)-3-hydroxyacyl-CoA = a
(2E)-enoyl-CoA + H2O", i.e. the D-specific hydratase 2 (EC 4.2.1.119). (The GOA IDA
annotations use the less specific parent GO:0004300 enoyl-CoA hydratase activity and
GO:0018812 3-hydroxyacyl-CoA dehydratase activity; GO:0080023 is the D-specific,
stereochemistry-correct term.)
2. GO:0106386 (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity β€” EC 1.1.1.n12.

Directly involved in: GO:0006635 fatty acid beta-oxidation; bile acid biosynthesis. Location:
GO:0005782 peroxisomal matrix.

πŸ“„ View Raw YAML

id: P51659
gene_symbol: HSD17B4
product_type: PROTEIN
status: INITIALIZED
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: >-
  HSD17B4 encodes the peroxisomal multifunctional enzyme type 2 (MFE-2/MFP-2), also known as
  D-bifunctional protein (DBP), a 736-residue enzyme of the peroxisomal matrix that catalyzes
  the second (hydration) and third (dehydrogenation) reactions of peroxisomal fatty-acid
  beta-oxidation with D (R) stereochemistry. It is a multidomain protein: an N-terminal
  (3R)-hydroxyacyl-CoA dehydrogenase domain of the short-chain dehydrogenase/reductase (SDR)
  family with an NAD(+)-binding Rossmann fold (historically named 17-beta-hydroxysteroid
  dehydrogenase type 4), a central D-specific enoyl-CoA hydratase 2 / (3R)-3-hydroxyacyl-CoA
  dehydratase domain of the MaoC/hot-dog fold, and a C-terminal SCP2-like sterol-carrier /
  lipid-transfer domain. The full-length protein is bifunctional and forms homodimers; in vivo
  it is proteolytically processed into separate dehydrogenase and hydratase chains. DBP is the
  main bifunctional enzyme handling very-long-chain fatty acids, 2-methyl-branched-chain
  (pristanic) acids, C27 bile-acid intermediates (di- and trihydroxycholestanoic acid), and
  long-chain dicarboxylic acids, and it participates in the peroxisomal beta-oxidation step that
  retroconverts C24:6n-3 to docosahexaenoic acid (DHA). Its 3-oxoacyl-CoA product is passed to
  the peroxisomal thiolase step (SCPx/ACAA1). Loss of function causes D-bifunctional protein
  deficiency, a severe Zellweger-like neonatal peroxisomal disorder, while milder hypomorphic
  alleles cause Perrault syndrome (sensorineural deafness with ovarian dysgenesis).
existing_annotations:
- term:
    id: GO:0106386
    label: (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: >-
      Phylogenetically-inferred (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity, the
      N-terminal dehydrogenase catalytic activity of DBP. This is one of the two core enzymatic
      functions and is directly supported by biochemistry (see IDA annotations to the same term).
    action: ACCEPT
    supported_by:
    - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
      supporting_text: "a (3R)-3-hydroxyacyl-CoA + NAD(+) = a 3-oxoacyl-CoA + NADH +"
- term:
    id: GO:0005777
    label: peroxisome
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: >-
      Phylogenetically-inferred peroxisomal localization; correct. DBP is a peroxisomal-matrix
      enzyme with a C-terminal PTS1-like targeting motif, consistent with IDA immunofluorescence.
    action: ACCEPT
    supported_by:
    - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Peroxisome"
- term:
    id: GO:0006635
    label: fatty acid beta-oxidation
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: >-
      Phylogenetically-inferred involvement in fatty acid beta-oxidation, the core biological
      process for DBP (it catalyzes reactions 2 and 3 of the peroxisomal beta-oxidation cycle).
    action: ACCEPT
    supported_by:
    - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
      supporting_text: "Bifunctional enzyme acting on the peroxisomal fatty acid"
- term:
    id: GO:0005777
    label: peroxisome
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: located_in
  review:
    summary: >-
      Electronic peroxisome localization (UniProt subcellular-location/ARBA). Correct and
      redundant with the experimentally-supported peroxisome/peroxisomal-matrix annotations.
    action: ACCEPT
- term:
    id: GO:0006629
    label: lipid metabolic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: involved_in
  review:
    summary: >-
      Electronic ARBA annotation to the very general parent term 'lipid metabolic process'. Not
      wrong but far less informative than fatty acid beta-oxidation; a high-level grouping term.
    action: MARK_AS_OVER_ANNOTATED
- term:
    id: GO:0016616
    label: oxidoreductase activity, acting on the CH-OH group of donors, NAD or NADP as acceptor
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: enables
  review:
    summary: >-
      Electronic ARBA annotation to a broad oxidoreductase grouping term. This is a correct but
      non-specific ancestor of the actual (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity;
      the specific term GO:0106386 should be used instead.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:0106386
      label: (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
- term:
    id: GO:0018812
    label: 3-hydroxyacyl-CoA dehydratase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: >-
      Electronic annotation to the dehydratase activity of the central hydratase-2 domain.
      Correct in essence; the D-specific term GO:0080023 ((2E)-enoyl-CoA hydratase activity,
      i.e. (3R)-3-hydroxyacyl-CoA = (2E)-enoyl-CoA + H2O) is the stereochemistry-precise term.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:0080023
      label: (2E)-enoyl-CoA hydratase activity
- term:
    id: GO:0033989
    label: 3alpha,7alpha,12alpha-trihydroxy-5beta-cholest-24-enoyl-CoA hydratase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: >-
      Electronic Rhea/EC-based annotation for the bile-acid (THCA-CoA) hydratase reaction
      (EC 4.2.1.107), a substrate-specific instance of DBP's hydratase-2 activity. This is a
      genuine, experimentally-supported substrate (di/trihydroxycholestanoic acid) so the term
      is retained as a substrate-specific non-core activity of the central hydratase domain.
    action: KEEP_AS_NON_CORE
    supported_by:
    - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
      supporting_text: "EC=4.2.1.107"
- term:
    id: GO:0080023
    label: (2E)-enoyl-CoA hydratase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: >-
      Electronic Rhea-based annotation to the D-specific (2E)-enoyl-CoA hydratase activity
      (EC 4.2.1.119); reaction (3R)-3-hydroxyacyl-CoA = (2E)-enoyl-CoA + H2O. This is the precise
      term for DBP's central hydratase-2 catalytic activity and is one of the two core functions.
    action: ACCEPT
    supported_by:
    - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
      supporting_text: "EC=4.2.1.119"
- term:
    id: GO:0102158
    label: very-long-chain (3R)-3-hydroxyacyl-CoA dehydratase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000116
  qualifier: enables
  review:
    summary: >-
      Electronic Rhea-based annotation to the VLCFA-specific instance of DBP's D-hydratase
      activity. Consistent with DBP being the main hydratase for very-long-chain fatty acids;
      a substrate-specific child of the core hydratase-2 activity.
    action: KEEP_AS_NON_CORE
    supported_by:
    - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
      supporting_text: "a very-long-chain (3R)-3-hydroxyacyl-CoA = a very-long-chain"
- term:
    id: GO:0106386
    label: (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000116
  qualifier: enables
  review:
    summary: >-
      Electronic Rhea-based annotation to the core dehydrogenase activity. Correct and
      redundant with the IDA/IBA annotations to the same term.
    action: ACCEPT
    supported_by:
    - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
      supporting_text: "a (3R)-3-hydroxyacyl-CoA + NAD(+) = a 3-oxoacyl-CoA + NADH +"
- term:
    id: GO:0006635
    label: fatty acid beta-oxidation
  evidence_type: IEA
  original_reference_id: GO_REF:0000041
  qualifier: involved_in
  review:
    summary: >-
      Electronic UniPathway-based annotation to fatty acid beta-oxidation, the core process.
      Correct and redundant with the IDA/IBA evidence.
    action: ACCEPT
    supported_by:
    - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
      supporting_text: "PATHWAY: Lipid metabolism; fatty acid beta-oxidation."
- term:
    id: GO:0005777
    label: peroxisome
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: >-
      Immunofluorescence (HPA) peroxisome localization. Directly supports the core peroxisomal
      localization of DBP.
    action: ACCEPT
- term:
    id: GO:0106386
    label: (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
  evidence_type: IDA
  original_reference_id: PMID:10706581
  qualifier: enables
  review:
    summary: >-
      Direct assay evidence for the (3R)-3-hydroxyacyl-CoA dehydrogenase activity, measured via
      recombinant human D-bifunctional protein used to generate the bile-acid dehydrogenation
      product. Core catalytic activity.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:10706581
      supporting_text: "expressing human D-bifunctional protein"
- term:
    id: GO:0106386
    label: (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
  evidence_type: IDA
  original_reference_id: PMID:15060085
  qualifier: enables
  review:
    summary: >-
      Direct enzyme-activity measurement of recombinant human DBP dehydrogenase on long-chain
      and dicarboxylic acyl-CoA substrates. Core catalytic activity.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:15060085
      supporting_text: "direct enzyme measurements with human recombinant"
- term:
    id: GO:0106386
    label: (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
  evidence_type: IDA
  original_reference_id: PMID:9089413
  qualifier: enables
  review:
    summary: >-
      Direct biochemical characterization of the purified/recombinant human bifunctional
      protein showing dehydrogenase activity; the full-length cDNA product has both dehydratase
      and dehydrogenase activities. Core catalytic activity, with defined kinetics.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:9089413
      supporting_text: "exhibited both the dehydratase and dehydrogenase activities"
- term:
    id: GO:0106386
    label: (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
  evidence_type: IDA
  original_reference_id: PMID:9482850
  qualifier: enables
  review:
    summary: >-
      Direct evidence that the D-bifunctional protein has 3-hydroxyacyl-CoA dehydrogenase
      activity, and expression of the Gly16Ser variant showed loss of this activity, confirming
      the dehydrogenase domain. Core catalytic activity.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:9482850
      supporting_text: "enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase activity"
- term:
    id: GO:0106386
    label: (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
  evidence_type: IMP
  original_reference_id: PMID:9482850
  qualifier: enables
  review:
    summary: >-
      Mutant-phenotype evidence (Gly16Ser in the NAD+-binding loop) abolishing the dehydrogenase
      activity, on the processed dehydrogenase chain (PRO_0000400082). Confirms the N-terminal
      dehydrogenase catalytic activity is required and mapped to this domain.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:9482850
      supporting_text: "the G46A mutation causes the loss of the 3-hydroxyacyl-CoA dehydrogenase activity"
- term:
    id: GO:0004303
    label: estradiol 17-beta-dehydrogenase [NAD(P)+] activity
  evidence_type: IDA
  original_reference_id: PMID:7487879
  qualifier: enables
  review:
    summary: >-
      From the original cloning paper, which reported a unidirectional oxidative 17-beta-HSD
      (estradiol dehydrogenase) activity when the enzyme was over-expressed in mammalian cells.
      This is the historical basis of the 17-beta-HSD type 4 name, but the physiological
      substrates are fatty-acyl-CoAs, not steroids; UniProt's FUNCTION section describes only
      fatty-acid/bile-acid metabolism. This steroid activity is an in-vitro side reaction and an
      over-annotation of the enzyme's core evolved role. Retained (experimental IDA) but flagged.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: PMID:7487879
      supporting_text: "17 beta-HSD IV enzyme displays a specific unidirectional oxidative 17 beta-HSD activity"
- term:
    id: GO:0004300
    label: enoyl-CoA hydratase activity
  evidence_type: IDA
  original_reference_id: PMID:10706581
  qualifier: enables
  review:
    summary: >-
      Direct evidence for enoyl-CoA hydratase activity (the enoyl-CoA of the bile-acid
      intermediate THCA is hydrated by recombinant human DBP). Correct; this is the parent of
      the D-specific hydratase-2 activity. MODIFY to the stereochemistry-precise term GO:0080023.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:0080023
      label: (2E)-enoyl-CoA hydratase activity
    supported_by:
    - reference_id: PMID:10706581
      supporting_text: "preincubating the enoyl-CoA of the bile acid intermediate THCA"
- term:
    id: GO:0004300
    label: enoyl-CoA hydratase activity
  evidence_type: IDA
  original_reference_id: PMID:15060085
  qualifier: enables
  review:
    summary: >-
      Direct enzyme-activity measurement of the DBP hydratase on long-chain / dicarboxylic
      substrates. Correct but non-specific; MODIFY to the D-specific hydratase-2 term GO:0080023.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:0080023
      label: (2E)-enoyl-CoA hydratase activity
    supported_by:
    - reference_id: PMID:15060085
      supporting_text: "direct enzyme measurements with human recombinant"
- term:
    id: GO:0004300
    label: enoyl-CoA hydratase activity
  evidence_type: IDA
  original_reference_id: PMID:9482850
  qualifier: enables
  review:
    summary: >-
      Direct evidence that DBP has enoyl-CoA hydratase activity; the enoyl-CoA hydratase
      activity was normal in a patient with an isolated dehydrogenase defect, confirming the
      distinct hydratase function. MODIFY to the D-specific term GO:0080023.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:0080023
      label: (2E)-enoyl-CoA hydratase activity
    supported_by:
    - reference_id: PMID:9482850
      supporting_text: "the enoyl-CoA hydratase activity of d -bifunctional protein was normal"
- term:
    id: GO:0006635
    label: fatty acid beta-oxidation
  evidence_type: IDA
  original_reference_id: PMID:10706581
  qualifier: involved_in
  review:
    summary: >-
      Direct evidence connecting DBP to peroxisomal beta-oxidation of bile-acid intermediates.
      Core biological process.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:10706581
      supporting_text: "peroxisomal oxidation of branched-chain fatty acids"
- term:
    id: GO:0006635
    label: fatty acid beta-oxidation
  evidence_type: IDA
  original_reference_id: PMID:15060085
  qualifier: involved_in
  review:
    summary: >-
      Direct evidence that DBP is one of the main enzymes in peroxisomal beta-oxidation of
      long-chain dicarboxylic acids. Core biological process.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:15060085
      supporting_text: "the main enzymes involved in beta-oxidation of C16DCA are SCOX, both LBP and DBP"
- term:
    id: GO:0006635
    label: fatty acid beta-oxidation
  evidence_type: IDA
  original_reference_id: PMID:9482850
  qualifier: involved_in
  review:
    summary: >-
      Direct evidence that DBP plays an essential, non-redundant role in the peroxisomal
      beta-oxidation pathway. Core biological process.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:9482850
      supporting_text: "plays an essential role in the peroxisomal Ξ²-oxidation pathway"
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-192331
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix in the context of the bile-acid
      (THCA-CoA hydration) reaction. Correct and the most precise localization term; the
      peroxisomal matrix is the functional compartment for DBP catalysis.
    action: ACCEPT
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-193455
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix (bile-acid intermediate
      dehydrogenation reaction). Correct core localization.
    action: ACCEPT
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-193508
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix (bile-acid intermediate reaction).
      Correct core localization.
    action: ACCEPT
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-193535
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix (bile-acid intermediate hydration
      reaction). Correct core localization.
    action: ACCEPT
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-2066778
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix (hydration step in DHA-synthesis
      beta-oxidation). Correct core localization.
    action: ACCEPT
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-2066780
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix (dehydrogenation step in
      DHA-synthesis beta-oxidation). Correct core localization.
    action: ACCEPT
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-389986
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix (pristanoyl-CoA hydration step).
      Correct core localization.
    action: ACCEPT
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-389995
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix (pristanoyl-CoA dehydrogenation
      step). Correct core localization.
    action: ACCEPT
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-390251
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix (VLCFA 3-hydroxyacyl-CoA
      dehydrogenation step). Correct core localization.
    action: ACCEPT
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-390252
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix (VLCFA enoyl-CoA hydration step).
      Correct core localization.
    action: ACCEPT
- term:
    id: GO:0005782
    label: peroxisomal matrix
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9033235
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS localizing DBP to the peroxisomal matrix as PEX5 import cargo (translocation
      from cytosol to matrix). Correct destination compartment for the imported enzyme.
    action: ACCEPT
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9033235
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS placing DBP in the cytosol as newly-synthesized PTS1 cargo before import.
      This reflects the transient import route, not the functional compartment; DBP acts in the
      peroxisomal matrix. Non-core.
    action: KEEP_AS_NON_CORE
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9033236
  qualifier: located_in
  review:
    summary: >-
      Reactome TAS placing DBP in the cytosol as PEX5 cargo binding the docking/translocation
      module. Import-route intermediate, not the functional compartment. Non-core.
    action: KEEP_AS_NON_CORE
- term:
    id: GO:0001649
    label: osteoblast differentiation
  evidence_type: HDA
  original_reference_id: PMID:16210410
  qualifier: involved_in
  review:
    summary: >-
      High-throughput proteomics screen of membrane-protein expression changes in a mesenchymal
      stem cell line undergoing osteoblast differentiation. DBP was detected as a differentially
      expressed protein, not shown to have any functional role in differentiation. An expression
      correlation, not a functional involvement; over-annotation.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: PMID:16210410
      supporting_text: "changes in expression of membrane protein markers"
- term:
    id: GO:0016020
    label: membrane
  evidence_type: HDA
  original_reference_id: PMID:16210410
  qualifier: located_in
  review:
    summary: >-
      From a membrane-protein proteomics screen; DBP co-fractionated in a membrane-enriched
      preparation. DBP is a soluble peroxisomal-matrix enzyme, not an integral membrane protein;
      this is a co-fractionation artifact / over-annotation of location.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: PMID:16210410
      supporting_text: "expression profiling of membrane proteins by quantitative"
- term:
    id: GO:0005777
    label: peroxisome
  evidence_type: IDA
  original_reference_id: PMID:15599942
  qualifier: located_in
  review:
    summary: >-
      Direct evidence (branched-chain fatty-acid beta-oxidation study in prostate) supporting
      peroxisomal localization and activity of DBP. Correct core localization.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:15599942
      supporting_text: "D-bifunctional protein (DBP)-is also upregulated in prostate cancer"
- term:
    id: GO:0042803
    label: protein homodimerization activity
  evidence_type: IDA
  original_reference_id: PMID:15644212
  qualifier: enables
  review:
    summary: >-
      Crystal structure of the human MFE-2 hydratase-2 domain, which forms a hot-dog-fold dimer;
      the full-length enzyme is a homodimer. Homodimerization is a real structural property but
      is a supporting feature of the active enzyme rather than a distinct core molecular
      function; retained as non-core.
    action: KEEP_AS_NON_CORE
    supported_by:
    - reference_id: PMID:15644212
      supporting_text: "having a two-domain subunit structure"
- term:
    id: GO:0018812
    label: 3-hydroxyacyl-CoA dehydratase activity
  evidence_type: IDA
  original_reference_id: PMID:9482850
  qualifier: enables
  review:
    summary: >-
      Direct evidence for the D-hydroxyacyl-CoA dehydratase / enoyl-CoA hydratase activity of
      DBP (normal hydratase activity in a dehydrogenase-defect patient). Correct; MODIFY to the
      stereochemistry-precise D term GO:0080023.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:0080023
      label: (2E)-enoyl-CoA hydratase activity
    supported_by:
    - reference_id: PMID:9482850
      supporting_text: "the enoyl-CoA hydratase activity of d -bifunctional protein was normal"
- term:
    id: GO:0005777
    label: peroxisome
  evidence_type: NAS
  original_reference_id: PMID:9482850
  qualifier: located_in
  review:
    summary: >-
      Non-traceable author statement that DBP is a peroxisomal beta-oxidation enzyme. Correct
      core localization, supported more strongly by IDA/TAS annotations.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:9482850
      supporting_text: "a new peroxisomal Ξ²-oxidation enzyme was recently described"
- term:
    id: GO:0036111
    label: very long-chain fatty-acyl-CoA metabolic process
  evidence_type: IDA
  original_reference_id: PMID:9482850
  qualifier: involved_in
  review:
    summary: >-
      Direct evidence that DBP is involved in VLCFA metabolism: DBP-deficient patients accumulate
      straight-chain very-long-chain fatty acids, and DBP may be the main VLCFA beta-oxidation
      enzyme. A biologically important substrate class; keep, though it is a specialization of
      the core fatty acid beta-oxidation process.
    action: KEEP_AS_NON_CORE
    supported_by:
    - reference_id: PMID:9482850
      supporting_text: "accumulates straight-chain fatty acids (VLCFA) both in plasma and fibroblasts"
- term:
    id: GO:0018812
    label: 3-hydroxyacyl-CoA dehydratase activity
  evidence_type: IDA
  original_reference_id: PMID:9089413
  qualifier: enables
  review:
    summary: >-
      Direct biochemical evidence: the purified human bifunctional protein has dehydratase
      activity, and a truncated C-terminal fragment retains only dehydratase activity, mapping
      it to the hydratase-2 domain. Correct; MODIFY to the D-specific term GO:0080023.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:0080023
      label: (2E)-enoyl-CoA hydratase activity
    supported_by:
    - reference_id: PMID:9089413
      supporting_text: "exhibited only the dehydratase activity"
- term:
    id: GO:0036112
    label: medium-chain fatty-acyl-CoA metabolic process
  evidence_type: IDA
  original_reference_id: PMID:9089413
  qualifier: involved_in
  review:
    summary: >-
      Direct evidence from kinetic characterization on medium-chain substrates (e.g. D-3-hydroxy-
      octanoyl-CoA, decanoyl-CoA). A substrate-specific specialization of DBP's beta-oxidation
      activity; retained as non-core.
    action: KEEP_AS_NON_CORE
    supported_by:
    - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
      supporting_text: "KM=10 uM for D-3-hydroxy-octanoyl-CoA"
- term:
    id: GO:0042803
    label: protein homodimerization activity
  evidence_type: IDA
  original_reference_id: PMID:9089413
  qualifier: enables
  review:
    summary: >-
      Direct evidence that the native enzyme is a homodimer (of the 77-kDa polypeptide).
      Structural property supporting the active enzyme; retained as non-core.
    action: KEEP_AS_NON_CORE
    supported_by:
    - reference_id: PMID:9089413
      supporting_text: "the native enzyme is a homodimer of 77-kDa"
- term:
    id: GO:0005778
    label: peroxisomal membrane
  evidence_type: HDA
  original_reference_id: PMID:21525035
  qualifier: located_in
  review:
    summary: >-
      HDA localization to the peroxisomal membrane, from a proteomics study whose subject is
      PEX14 and microtubule-based peroxisome motility (DBP is not its focus). DBP is a soluble
      matrix enzyme; membrane co-purification reflects peroxisome-membrane proteome preparation,
      not integral membrane localization. Over-annotation of location.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: PMID:21525035
      supporting_text: "isolating native peroxisomal membrane protein complexes from cultured human cells"
- term:
    id: GO:0006635
    label: fatty acid beta-oxidation
  evidence_type: IDA
  original_reference_id: PMID:10400999
  qualifier: involved_in
  review:
    summary: >-
      Direct evidence: DBP is involved in peroxisomal beta-oxidation of VLCFAs, branched-chain
      fatty acids and bile-acid intermediates; a new hydratase-domain deficiency was defined
      here. Core biological process.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:10400999
      supporting_text: "D-bifunctional protein is involved in the peroxisomal beta-oxidation of very long chain fatty acids, branched chain fatty acids and bile acid intermediates"
- term:
    id: GO:0018812
    label: 3-hydroxyacyl-CoA dehydratase activity
  evidence_type: IDA
  original_reference_id: PMID:10400999
  qualifier: enables
  review:
    summary: >-
      Direct evidence for the enoyl-CoA hydratase (dehydratase) domain activity; two patients had
      an isolated defect in the enoyl-CoA hydratase domain of DBP (Asn457Tyr). Correct; MODIFY to
      the D-specific term GO:0080023.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:0080023
      label: (2E)-enoyl-CoA hydratase activity
    supported_by:
    - reference_id: PMID:10400999
      supporting_text: "an isolated defect in the enoyl-CoA hydratase domain of D-bifunctional protein"
- term:
    id: GO:0005777
    label: peroxisome
  evidence_type: NAS
  original_reference_id: PMID:7487879
  qualifier: located_in
  review:
    summary: >-
      Non-traceable author statement of peroxisomal localization from the original cloning paper
      (the C-terminal region is similar to sterol carrier protein 2, a peroxisomal marker).
      Correct core localization, supported more strongly by IDA/TAS annotations.
    action: ACCEPT
    supported_by:
    - reference_id: PMID:7487879
      supporting_text: "amino acids 596-736 which are similar to human sterol"
- term:
    id: GO:0008209
    label: androgen metabolic process
  evidence_type: IDA
  original_reference_id: PMID:7487879
  qualifier: involved_in
  review:
    summary: >-
      From the original cloning paper reporting 17-beta-HSD (steroid) activity in over-expressing
      cells. DBP's physiological substrates are fatty-acyl-CoAs, not androgens; UniProt's FUNCTION
      section describes only fatty-acid/bile-acid metabolism. This steroid-metabolism process is a
      side reaction and an over-annotation of the enzyme's core role. Retained (experimental IDA)
      but flagged.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: PMID:7487879
      supporting_text: "Reactions of oestrogens and androgens at position C-17 are catalysed by 17 beta-hydroxysteroid dehydrogenases"
- term:
    id: GO:0008210
    label: estrogen metabolic process
  evidence_type: IDA
  original_reference_id: PMID:7487879
  qualifier: involved_in
  review:
    summary: >-
      From the original cloning paper reporting oxidative 17-beta-estradiol dehydrogenase activity
      in over-expressing cells. As with androgen metabolism, this is an in-vitro steroid side
      activity, not the enzyme's physiological (fatty-acid) role; over-annotation. Retained
      (experimental IDA) but flagged.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: PMID:7487879
      supporting_text: "17 beta-HSD IV enzyme displays a specific unidirectional oxidative 17 beta-HSD activity"
core_functions:
- description: >-
    D-specific enoyl-CoA hydratase 2 (D-3-hydroxyacyl-CoA dehydratase) activity: the central
    MaoC/hot-dog-fold domain hydrates a (2E)-enoyl-CoA to a (3R)-3-hydroxyacyl-CoA (EC 4.2.1.119),
    the second reaction of each peroxisomal beta-oxidation cycle, acting on very-long-chain,
    2-methyl-branched (pristanic) and bile-acid-intermediate acyl-CoAs in the peroxisomal matrix.
  supported_by:
  - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
    supporting_text: "hydration of 2-enoyl-CoA (trans-2-enoyl-CoA) to"
  - reference_id: PMID:9089413
    supporting_text: "exhibited only the dehydratase activity"
  molecular_function:
    id: GO:0080023
    label: (2E)-enoyl-CoA hydratase activity
  directly_involved_in:
  - id: GO:0006635
    label: fatty acid beta-oxidation
  locations:
  - id: GO:0005782
    label: peroxisomal matrix
- description: >-
    (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity: the N-terminal SDR/Rossmann-fold domain
    oxidizes a (3R)-3-hydroxyacyl-CoA with NAD+ to a 3-oxoacyl-CoA (EC 1.1.1.n12), the third
    reaction of each peroxisomal beta-oxidation cycle; the 3-oxoacyl-CoA product is handed to the
    peroxisomal thiolase step. Acts on the same VLCFA, branched-chain and bile-acid substrates.
  supported_by:
  - reference_id: file:human/HSD17B4/HSD17B4-uniprot.txt
    supporting_text: "dehydrogenation of (3R)-3-"
  - reference_id: PMID:9482850
    supporting_text: "enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase activity"
  molecular_function:
    id: GO:0106386
    label: (3R)-3-hydroxyacyl-CoA dehydrogenase (NAD+) activity
  directly_involved_in:
  - id: GO:0006635
    label: fatty acid beta-oxidation
  locations:
  - id: GO:0005782
    label: peroxisomal matrix
proposed_new_terms: []
suggested_questions:
- question: >-
    Given that DBP's physiological substrates are fatty-acyl-CoAs, should the historical
    17-beta-hydroxysteroid dehydrogenase (estradiol/androgen/estrogen) activities be retained as
    curated functions, or reclassified as in-vitro side activities?
- question: >-
    Which peroxisomal beta-oxidation substrate classes (VLCFA vs pristanic/bile-acid vs
    dicarboxylic vs PUFA/DHA) depend most non-redundantly on DBP versus the L-bifunctional
    protein (EHHADH)?
suggested_experiments:
- description: >-
    Substrate-resolved metabolomics of DBP-null versus EHHADH-null cells to quantify the
    non-redundant contribution of DBP to each acyl-CoA class (VLCFA, pristanoyl, DHCA/THCA,
    C16DCA, C24:6n-3).
- description: >-
    Structure-guided mutagenesis of the hydratase-2 substrate-binding loops to test whether the
    reported steroid dehydrogenase activity and the fatty-acyl dehydrogenase activity can be
    separated, clarifying the physiological relevance of the 17-beta-HSD activity.
references:
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000041
  title: Gene Ontology annotation based on UniPathway vocabulary mapping
  findings: []
- id: GO_REF:0000052
  title: Gene Ontology annotation based on curation of immunofluorescence data
  findings: []
- id: GO_REF:0000116
  title: Automatic Gene Ontology annotation based on Rhea mapping
  findings: []
- id: GO_REF:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning models
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:10400999
  title: 'Enoyl-CoA hydratase deficiency: identification of a new type of D-bifunctional
    protein deficiency.'
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      PubMed-verified. Defines an isolated hydratase-domain deficiency of DBP (Asn457Tyr) and
      states DBP's role in beta-oxidation of VLCFA, branched-chain and bile-acid intermediates.
- id: PMID:10706581
  title: Peroxisomal fatty acid oxidation disorders and 58 kDa sterol carrier protein
    X (SCPx). Activity measurements in liver and fibroblasts using a newly developed
    method.
  findings: []
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: >-
      Abstract-only cache. Uses recombinant human D-bifunctional protein to generate the
      bile-acid enoyl-CoA substrate; supports DBP hydratase/dehydrogenase activity on bile-acid
      intermediates. Primary focus is SCPx, so relevance is medium.
- id: PMID:15060085
  title: Identification of the peroxisomal beta-oxidation enzymes involved in the
    degradation of long-chain dicarboxylic acids.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Abstract-only cache. Direct enzyme measurements with recombinant human DBP; identifies DBP
      as one of the main enzymes in peroxisomal beta-oxidation of C16 dicarboxylic acid.
- id: PMID:15599942
  title: Peroxisomal branched chain fatty acid beta-oxidation pathway is upregulated
    in prostate cancer.
  findings: []
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: >-
      Abstract-only cache. Shows DBP is upregulated with increased activity in prostate cancer;
      supports peroxisomal localization/activity. Physiological/disease context rather than core
      mechanism.
- id: PMID:15644212
  title: Crystal structure of 2-enoyl-CoA hydratase 2 from human peroxisomal multifunctional
    enzyme type 2.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Abstract-only cache. Crystal structure of the human MFE-2 hydratase-2 domain; explains
      accommodation of bulky C26, pristanic and DHCA/THCA CoA esters and supports homodimerization.
- id: PMID:16210410
  title: Differential expression profiling of membrane proteins by quantitative proteomics
    in a human mesenchymal stem cell line undergoing osteoblast differentiation.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: >-
      Abstract-only cache. High-throughput membrane-proteomics screen; DBP detected as a
      differentially expressed protein. Basis of the osteoblast-differentiation and membrane
      annotations, both of which are over-annotations (expression change / co-fractionation).
- id: PMID:21525035
  title: PEX14 is required for microtubule-based peroxisome motility in human cells.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: >-
      Abstract-only cache. Study of PEX14 and peroxisome motility, not HSD17B4; DBP appears only
      as a co-purified peroxisomal-membrane-preparation protein. Basis of an over-annotated
      peroxisomal-membrane location.
- id: PMID:7487879
  title: Molecular cloning of a novel widely expressed human 80 kDa 17 beta-hydroxysteroid
    dehydrogenase IV.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Abstract-only cache. Original cloning of the 736-aa protein as 17-beta-HSD IV; reports a
      unidirectional oxidative 17-beta-HSD activity. Source of the steroid-activity annotations,
      which are in-vitro side activities relative to the enzyme's physiological fatty-acid role.
- id: PMID:9089413
  title: Structure of D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase
    bifunctional protein.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Abstract-only cache. Shows the full-length human enzyme is bifunctional (dehydratase +
      dehydrogenase), a truncated C-terminal fragment retains only dehydratase, and the native
      enzyme is a homodimer; cDNA identical to 17-beta-HSD IV. Directly supports both core MFs.
- id: PMID:9482850
  title: 'Peroxisomal D-hydroxyacyl-CoA dehydrogenase deficiency: resolution of the
    enzyme defect and its molecular basis in bifunctional protein deficiency.'
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Full text available (PMC19272). First case of DBP deficiency; Gly16Ser in the NAD+-binding
      loop abolishes the dehydrogenase activity while hydratase activity is normal; DBP is
      essential and non-redundant, and likely the main VLCFA beta-oxidation enzyme.
- id: PMID:11734571
  title: Identification of the peroxisomal beta-oxidation enzymes involved in the
    biosynthesis of docosahexaenoic acid.
  findings: []
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: >-
      Abstract-only cache. Shows DBP is among the main enzymes in the peroxisomal beta-oxidation
      of C24:6n-3 to DHA (C22:6n-3). Cited by UniProt for the PUFA/DHA function; supports the
      DHA-synthesis role.
- id: Reactome:R-HSA-192331
  title: 3alpha,7alpha,12alpha-trihydroxy-5beta-cholest-24-enoyl-CoA (THCA-CoA) is
    hydrated to (24R, 25R) 3alpha,7alpha,12alpha,24-tetrahydroxy-5beta-cholestanoyl-CoA
  findings: []
- id: Reactome:R-HSA-193455
  title: (24R, 25R) 3alpha,7alpha,12alpha,24-tetrahydroxy-5beta-cholestanoyl-CoA is
    oxidized to 3alpha,7alpha,12alpha-trihydroxy-5beta-cholest-24-one-CoA
  findings: []
- id: Reactome:R-HSA-193508
  title: (24R, 25R) 3alpha,7alpha,24-trihydroxy-5beta-cholestanoyl-CoA is oxidized
    to 3alpha,7alpha-dihydroxy-5beta-cholest-24-one-CoA
  findings: []
- id: Reactome:R-HSA-193535
  title: 25(S) 3alpha,7alpha-dihydroxy-5beta-cholest-24-enoyl-CoA is hydrated to (24R,
    25R) 3alpha,7alpha,24-trihydroxy-5beta-cholestanoyl-CoA
  findings: []
- id: Reactome:R-HSA-2066778
  title: Hydration of delta2-tetracosaheptaenoyl-CoA to 3-hydroxy tetracosahexaenoyl-CoA
  findings: []
- id: Reactome:R-HSA-2066780
  title: Dehydrogenation of 3-hydroxy tetracosahexaenoyl-CoA
  findings: []
- id: Reactome:R-HSA-389986
  title: trans-2,3-dehydropristanoyl-CoA + H2O => 3-hydroxypristanoyl-CoA
  findings: []
- id: Reactome:R-HSA-389995
  title: 3-hydroxypristanoyl-CoA + NAD+ => 3-ketoxypristanoyl-CoA + NADH + H+
  findings: []
- id: Reactome:R-HSA-390251
  title: HSD17B4 dehydrogenates 3-hydroxyhexacosanoyl-CoA
  findings: []
- id: Reactome:R-HSA-390252
  title: HSD17B4 hydrates trans-2,3-dehydrohexacosanoyl-CoA
  findings: []
- id: Reactome:R-HSA-9033235
  title: Cargo of PEX5S,L translocates from the cytosol to the peroxisomal matrix
  findings: []
- id: Reactome:R-HSA-9033236
  title: PEX5S,L:Cargo binds PEX13:PEX14:PEX2:PEX10:PEX12 (Docking and Translocation
    Module)
  findings: []