CYP1B1

Summary: CYP1B1 contributes to trabecular-meshwork development and maintenance.

Reason: The exact Q64429 mouse IMP record is supported by 23979599: Cyp1b1 loss alters trabecular-meshwork collagen organization, periostin expression and oxidative-stress responses. Human TM1 knockdown experiments provide additional cell-context evidence, while NAC and periostin experiments connect the phenotype to redox-dependent extracellular-matrix organization. Retain the developmental role as contextual; neither the glaucoma phenotype nor rescue alone identifies a particular CYP1B1 substrate reaction.

Summary: CYP1B1 contributes to trabecular-meshwork development and maintenance.

Reason: The exact Q64429 mouse IMP record is supported by 23979599: Cyp1b1 loss alters trabecular-meshwork collagen organization, periostin expression and oxidative-stress responses. Human TM1 knockdown experiments provide additional cell-context evidence, while NAC and periostin experiments connect the phenotype to redox-dependent extracellular-matrix organization. Retain the developmental role as contextual; neither the glaucoma phenotype nor rescue alone identifies a particular CYP1B1 substrate reaction.

Summary: The arachidonate and retinoid assays support a reduced-flavoprotein-dependent monooxygenase.

Reason: The human CYP1B1 retinoid and arachidonate assays directly demonstrate NADPH/POR-supported monooxygenation. GO:0016712 identifies the immediate reduced-flavoprotein electron donor more precisely while retaining substrate breadth. The reconstituted system used rabbit POR and an N-terminally modified human enzyme; the human CYP1B1 Supersome product pattern corroborated the arachidonate result. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The human estradiol experiment supports flavoprotein-linked monooxygenation.

Reason: The inspected 23821647 Methods use N-terminally modified human CYP1B1 with human NADPH-cytochrome P450 reductase. Product analysis directly measures 2- and 4-hydroxyestradiol formation. GO:0016712 specifies the immediate reduced-flavoprotein donor without narrowing the enzyme to one substrate or conflating mouse and human regioselectivity. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The combined domain and mouse-enzyme evidence supports flavoprotein-linked monooxygenation.

Reason: The actual InterPro matches cover the P450 catalytic region, and the exact Q64429 IDA records include 15258110 and 23821647. Those assays and independent human reconstitution show electrons delivered through P450 reductase. Refine to GO:0016712 rather than using the family fold alone to infer a specific substrate. The original combined-method source list remains unchanged. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The modeled arachidonate reaction belongs to flavoprotein-linked monooxygenation.

Reason: The actual Reactome 16-HETE event reaches CYP1B1 through the CYP(1) catalyst set and the Q16678 reference entity. Human CYP1B1 reconstitution in 15258110 supports the reduced-POR-dependent catalytic class, so GO:0016712 is more informative than monooxygenase activity. At the event-specific product level, 16/17/18-HETE were measured as a grouped chromatographic peak. The class refinement does not turn every modeled terminal regioisomer into an independently resolved human measurement. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The modeled arachidonate reaction belongs to flavoprotein-linked monooxygenation.

Reason: The actual Reactome 19-HETE event reaches CYP1B1 through the CYP(2) catalyst set and the Q16678 reference entity. Human CYP1B1 reconstitution in 15258110 supports the reduced-POR-dependent catalytic class, so GO:0016712 is more informative than monooxygenase activity. At the event-specific product level, 19-HETE can coelute with 20-HETE; the assay does not separately quantify 19-HETE. The class refinement does not turn every modeled terminal regioisomer into an independently resolved human measurement. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The modeled arachidonate reaction belongs to flavoprotein-linked monooxygenation.

Reason: The actual Reactome 5,6-EET event reaches CYP1B1 through the CYP(4) catalyst set and the Q16678 reference entity. Human CYP1B1 reconstitution in 15258110 supports the reduced-POR-dependent catalytic class, so GO:0016712 is more informative than monooxygenase activity. At the event-specific product level, the human experiment resolves the 5,6-EET regioisomer. The class refinement does not turn every modeled terminal regioisomer into an independently resolved human measurement. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The modeled arachidonate reaction belongs to flavoprotein-linked monooxygenation.

Reason: The actual Reactome 8,9-EET event reaches CYP1B1 through the CYP(5) catalyst set and the Q16678 reference entity. Human CYP1B1 reconstitution in 15258110 supports the reduced-POR-dependent catalytic class, so GO:0016712 is more informative than monooxygenase activity. At the event-specific product level, the human experiment resolves the 8,9-EET regioisomer. The class refinement does not turn every modeled terminal regioisomer into an independently resolved human measurement. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The modeled arachidonate reaction belongs to flavoprotein-linked monooxygenation.

Reason: The actual Reactome 20-HETE event reaches CYP1B1 through the CYP(3) catalyst set and the Q16678 reference entity. Human CYP1B1 reconstitution in 15258110 supports the reduced-POR-dependent catalytic class, so GO:0016712 is more informative than monooxygenase activity. At the event-specific product level, 20-HETE was matched against a standard, with possible 19-HETE coelution. The class refinement does not turn every modeled terminal regioisomer into an independently resolved human measurement. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The wild-type catalytic class is supported, while the cited model describes defective variants.

Reason: R-HSA-5605147 is explicitly a FailedReaction. Its catalyst set contains nine disease variants linked to the Q16678 reference sequence; this is not nine active isoforms or an assay of wild-type turnover. Retain the biologically established gene-level monooxygenation and refine its donor class to GO:0016712 using the independent human reconstitution in 23821647. Preserve the failed-reaction provenance and do not credit the listed variants with wild-type activity. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The modeled arachidonate reaction belongs to flavoprotein-linked monooxygenation.

Reason: The actual Reactome 11,12-EET event reaches CYP1B1 through the CYP(5) catalyst set and the Q16678 reference entity. Human CYP1B1 reconstitution in 15258110 supports the reduced-POR-dependent catalytic class, so GO:0016712 is more informative than monooxygenase activity. At the event-specific product level, the human experiment resolves the 11,12-EET regioisomer. The class refinement does not turn every modeled terminal regioisomer into an independently resolved human measurement. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The modeled arachidonate reaction belongs to flavoprotein-linked monooxygenation.

Reason: The actual Reactome 17-HETE event reaches CYP1B1 through the CYP(1) catalyst set and the Q16678 reference entity. Human CYP1B1 reconstitution in 15258110 supports the reduced-POR-dependent catalytic class, so GO:0016712 is more informative than monooxygenase activity. At the event-specific product level, 16/17/18-HETE were measured as a grouped peak, with individual identities based on earlier HPLC assignments. The class refinement does not turn every modeled terminal regioisomer into an independently resolved human measurement. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The modeled arachidonate reaction belongs to flavoprotein-linked monooxygenation.

Reason: The actual Reactome 18-HETE event reaches CYP1B1 through the CYP(1) catalyst set and the Q16678 reference entity. Human CYP1B1 reconstitution in 15258110 supports the reduced-POR-dependent catalytic class, so GO:0016712 is more informative than monooxygenase activity. At the event-specific product level, 16/17/18-HETE were measured as a grouped peak, with individual identities based on earlier HPLC assignments. The class refinement does not turn every modeled terminal regioisomer into an independently resolved human measurement. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The modeled arachidonate reaction belongs to flavoprotein-linked monooxygenation.

Reason: The actual Reactome 14,15-EET event reaches CYP1B1 through the CYP(5) catalyst set and the Q16678 reference entity. Human CYP1B1 reconstitution in 15258110 supports the reduced-POR-dependent catalytic class, so GO:0016712 is more informative than monooxygenase activity. At the event-specific product level, the human experiment resolves the 14,15-EET regioisomer. The class refinement does not turn every modeled terminal regioisomer into an independently resolved human measurement. GO:0016712 is already represented by other retained source assertions; this replacement refines the donor-dependent chemistry of this source and does not add a separate activity.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: Catalytic heme supplies the iron cofactor.

Reason: CYP1B1 is a heme-thiolate enzyme whose catalytic heme contains iron. The authenticated official sequence has the heme axial-ligand cysteine at residue 470, and the human engineered CYP1B1 crystal structure contains heme. Retain iron-cofactor binding without implying transport, storage or a separate physiological iron-handling function.

Summary: CYP1B1 associates with the receptor tyrosine kinase TEK.

Reason: All six current literal IntAct records for the original Q16678/Q02763 pair agree with the inspected 28620713 co-immunoprecipitation study. HA-TEK and GFP-CYP1B1 associate in HEK293 cells; TEK intracellular residues 816–1124 retain the strong association whereas the extracellular fragment binds weakly. Official Q02763 is the angiopoietin receptor tyrosine kinase. GO:0030971 captures the experimentally supported partner class. Co-immunoprecipitation does not establish a purified binary interface, ligand agonism or activation of TEK by CYP1B1.

Proposed replacements: receptor tyrosine kinase binding

Summary: Mitochondrial association is supported in a conditional mouse context.

Reason: The traced Q64429 IMP evidence in 23692925 uses female mouse WT/knockout tissues and TCDD induction. ER- and mitochondria-enriched fractions contain the induced CYP1B1 band, with knockout specificity controls and acknowledged fraction cross-contamination. Human HPA staining is labeled uncertain, not a strong independent localization assay. Retain mitochondrial association as contextual ortholog inference without a constitutive human mitochondrial core, an established import-cleavage site or a membrane-topology claim. The actual PTN001210461 mitochondrial IBD is on the reconstructed target path; its mouse and rat sources are not interpreted as pairwise similarity scores. ORGANELLES check (2026-10-25), the action holds. The ER/MAM confound is addressed in PMID:23692925, which used nonhepatic tissues, the microsomal marker POR and the mitochondrial marker PHB, and the internal control of Cyp1a1(mc/mc) mice whose ER-only CYP1A1 was absent from the mitochondrial fraction; TCDD-induced CYP1B1 was in both fractions and absent from Cyp1b1 knockouts. The organelle claim is therefore supported for the mouse ortholog, as an inducible, minor pool beside the ER. Stays at the root (rule 4). The only sub-mitochondrial line is by analogy to CYP1A1, which the Avadhani work places in the inner membrane via an N-terminal signal; no sub-mitochondrial assay exists for CYP1B1, and its UniProt topology is a peripheral ER-membrane protein. PAINT check, PTN001210461 (taxon 6072) has two GO:0005739 IBD seeds, MGI:88590 (mouse Cyp1b1, the PMID:23692925 data) and RGD:2458 (rat Cyp1a1), both direct mitochondrial cases, so the node placement is reasonable. Qualifier note (is_active_in), this review does not show CYP1B1 activity in the organelle; PMID:23692925 detects protein only, and mitochondrial monooxygenase activity with adrenodoxin is established for CYP1A1, not CYP1B1, so located_in would be the claim the evidence supports.

Summary: Mitochondrial association is supported in a conditional mouse context.

Reason: The traced Q64429 IMP evidence in 23692925 uses female mouse WT/knockout tissues and TCDD induction. ER- and mitochondria-enriched fractions contain the induced CYP1B1 band, with knockout specificity controls and acknowledged fraction cross-contamination. Human HPA staining is labeled uncertain, not a strong independent localization assay. Retain mitochondrial association as contextual ortholog inference without a constitutive human mitochondrial core, an established import-cleavage site or a membrane-topology claim. ORGANELLES check (2026-10-25), the action holds. The ER/MAM confound is addressed in PMID:23692925, which used nonhepatic tissues, the microsomal marker POR and the mitochondrial marker PHB, and the internal control of Cyp1a1(mc/mc) mice whose ER-only CYP1A1 was absent from the mitochondrial fraction; TCDD-induced CYP1B1 was in both fractions and absent from Cyp1b1 knockouts. The organelle claim is therefore supported for the mouse ortholog, as an inducible, minor pool beside the ER. Stays at the root (rule 4). The only sub-mitochondrial line is by analogy to CYP1A1, which the Avadhani work places in the inner membrane via an N-terminal signal; no sub-mitochondrial assay exists for CYP1B1, and its UniProt topology is a peripheral ER-membrane protein.

Summary: Mitochondrial association is supported in a conditional mouse context.

Reason: The traced Q64429 IMP evidence in 23692925 uses female mouse WT/knockout tissues and TCDD induction. ER- and mitochondria-enriched fractions contain the induced CYP1B1 band, with knockout specificity controls and acknowledged fraction cross-contamination. Human HPA staining is labeled uncertain, not a strong independent localization assay. Retain mitochondrial association as contextual ortholog inference without a constitutive human mitochondrial core, an established import-cleavage site or a membrane-topology claim. ORGANELLES check (2026-10-25), the action holds. The ER/MAM confound is addressed in PMID:23692925, which used nonhepatic tissues, the microsomal marker POR and the mitochondrial marker PHB, and the internal control of Cyp1a1(mc/mc) mice whose ER-only CYP1A1 was absent from the mitochondrial fraction; TCDD-induced CYP1B1 was in both fractions and absent from Cyp1b1 knockouts. The organelle claim is therefore supported for the mouse ortholog, as an inducible, minor pool beside the ER. Stays at the root (rule 4). The only sub-mitochondrial line is by analogy to CYP1A1, which the Avadhani work places in the inner membrane via an N-terminal signal; no sub-mitochondrial assay exists for CYP1B1, and its UniProt topology is a peripheral ER-membrane protein.

Summary: CYP1B1 is associated with the endoplasmic-reticulum membrane.

Reason: Endoplasmic-reticulum membrane association is consistent with microsomal CYP1B1 biology, the official by-similarity localization and the structural paper’s discussion of the N-terminal targeting region. The purified structure removed that region and is not a direct native-cell localization assay. No integral-versus-peripheral topology refinement is needed for this term.

Summary: The mouse ER-localization evidence supports the conserved microsomal location.

Reason: The exact mouse Q64429 experimental record traces to PMID:23692925. In female WT and Cyp1b1-null mice, TCDD treatment induced a CYP1B1-specific band in ER-enriched fractions from several tissues; the knockout and fraction markers were examined, with some cross-contamination acknowledged. This supports transfer of the ER-membrane location together with established human microsomal enzyme biology. It is a mouse localization assay, not a direct human topology or membrane-orientation measurement.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-211951 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-2161795 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-2161814 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-2161890 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-2161899 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-2161940 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-5605147 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event. This particular route uses disease-variant entities in a failed reaction; its location does not imply retained variant catalysis.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-9915971 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-9915992 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-9915993 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event.

Summary: The modeled CYP1B1 entity occupies the endoplasmic-reticulum membrane.

Reason: The complete selected Reactome:R-HSA-9915997 route reaches CYP1B1 physical entities annotated at the endoplasmic-reticulum membrane and then the Q16678 reference entity. This agrees with the established microsomal catalytic context and the independently traced mouse fractionation evidence. Event-wide cytosol or lumen compartments are not transferred to the enzyme simply because they occur on the same event.

Summary: The phylogenetic placement is valid, but the exact steroid-catabolic scope remains unresolved.

Reason: The actual steroid-catabolic IBD at PTN001210461 is on the target path and its literal source P05177 is human CYP1A2. A current P05177 IMP record cites 18356043, whose complete available abstract emphasizes lynestrenol bioactivation and norethindrone metabolism by CYP2C9, CYP2C19 and CYP3A4; the full original could not be inspected. This does not establish a wrong-gene citation or invalid node. Human CYP1B1 steroid hydroxylation is clear, but the retrieved evidence does not independently settle the stronger breakdown/clearance scope of this exact inherited term. Preserve the positive steroid/estrogen metabolic annotations while leaving this source-specific catabolic assertion unresolved.

Summary: CYP1B1 directly metabolizes xenobiotic coumarin substrates.

Reason: The complete 22888116 abstract explicitly reports human CYP1B1 O-deethylation of 7-ethoxycoumarin and 7-ethoxy-4-(trifluoromethyl)coumarin, including kinetic isotope effects and phospholipid-dependent kinetic changes. These are direct substrate transformations, not merely a xenobiotic-response phenotype. Full Methods remained inaccessible; the positive catalytic assertion is retained with curator deference and without inventing an exact construct.

Summary: The statement annotation correctly identifies CYP1B1 as a xenobiotic-metabolizing enzyme.

Reason: The complete 16982751 abstract explicitly identifies CYP1B1 procarcinogen metabolism and measures changes in endogenous enzyme activity when miR-27b repression is manipulated. The paper primarily studies regulation of CYP1B1, not a miRNA function performed by CYP1B1. Its NAS metabolic statement is independently corroborated by direct human xenobiotic turnover in 22888116 and 36442682. The attempted full-original route failed and no additional experimental details are inferred.

Summary: The donor study establishes NO regulation but not a CYP1B1-performed NO biosynthetic step.

Reason: The exact mouse Q64429 IMP source PMID:20032512 establishes regulation of endothelial NO availability: chronic Cyp1b1 knockout or siRNA reduces eNOS expression and NO-associated fluorescence, whereas acute CYP1B1 restoration raises NO availability without restoring eNOS. The DAF-FM assay reports NO-associated species, and the original retains synthesis and bioavailability as alternatives. The measured effects are consistent with redox/eNOS regulation, but no CYP1B1-performed chemical step, structural contribution or cofactor contribution to NO formation is established. The specific biosynthetic-process transfer therefore exceeds the performed role resolved by this source and is over-annotated. This does not deny the positive endothelial regulatory effects, prove that NO synthesis is unaffected, or require every valid participant in biosynthesis to be an NO synthase. No narrower regulation annotation is proposed because synthesis versus preservation remains unresolved.

Summary: The donor study establishes NO regulation but not a CYP1B1-performed NO biosynthetic step.

Reason: The exact mouse Q64429 IMP source PMID:20032512 establishes regulation of endothelial NO availability: chronic Cyp1b1 knockout or siRNA reduces eNOS expression and NO-associated fluorescence, whereas acute CYP1B1 restoration raises NO availability without restoring eNOS. The DAF-FM assay reports NO-associated species, and the original retains synthesis and bioavailability as alternatives. The measured effects are consistent with redox/eNOS regulation, but no CYP1B1-performed chemical step, structural contribution or cofactor contribution to NO formation is established. The specific biosynthetic-process transfer therefore exceeds the performed role resolved by this source and is over-annotated. This does not deny the positive endothelial regulatory effects, prove that NO synthesis is unaffected, or require every valid participant in biosynthesis to be an NO synthase. No narrower regulation annotation is proposed because synthesis versus preservation remains unresolved.

Summary: CYP1B1 affects cell adhesion in trabecular-meshwork cells.

Reason: The literal mouse Q64429 IMP record in 23979599 is supported by functional adhesion measurements: Cyp1b1 loss increases attachment to fibronectin and vitronectin, and the study also tests CYP1B1 knockdown in human TM1 cells. Periostin, oxidative stress and extracellular-matrix changes provide a context for this contribution. Retain the broad cell-adhesion involvement as non-core without describing CYP1B1 as an adhesion receptor or importing the separate pericyte integrin mechanism into this assay.

Summary: CYP1B1 affects cell adhesion in trabecular-meshwork cells.

Reason: The literal mouse Q64429 IMP record in 23979599 is supported by functional adhesion measurements: Cyp1b1 loss increases attachment to fibronectin and vitronectin, and the study also tests CYP1B1 knockdown in human TM1 cells. Periostin, oxidative stress and extracellular-matrix changes provide a context for this contribution. Retain the broad cell-adhesion involvement as non-core without describing CYP1B1 as an adhesion receptor or importing the separate pericyte integrin mechanism into this assay.

Summary: The original steroid assay specifically demonstrates estrogen metabolism.

Reason: The human CYP1B1 estradiol-hydroxylation experiment supports the original broad steroid-metabolism assertion. The retained GO:0008210 estrogen metabolic process already entails GO:0008202, so this source is TOO_GENERAL rather than a proposal to add an already represented estrogen process. The complete abstract reports estradiol 4-hydroxylation and lipid-dependent kinetics; full original Methods remain inaccessible. This is a specificity judgment, not rejection of the measured chemistry.

Summary: The broad steroid-metabolism rule is true but already covered by the supported estrogen pathway.

Reason: The actual ARBA00027309 condition sets match the authenticated human features. Current typed ancestry places accepted estrogen metabolic process under steroid metabolic process. This broad rule adds no distinct substrate or pathway role beyond the supported estrogen metabolism and other specific steroid activities; its validity is not rejected.

Summary: The estrogen-metabolism IBD is experimentally grounded and inherited by CYP1B1.

Reason: PTN001210461 is on the actual human target path and the literal estrogen-metabolism IBD has the listed mouse, rat and human CYP descendant sources. The current exact donor records include human Q16678 assays in 11555828, 12865317 and 23821647. Direct human 2-/4-hydroxylation supports the inherited metabolic role; self-descendant evidence is valid, not circular. The different human and rodent regioselectivities are retained rather than treated as identical kinetics.

Summary: Human CYP1B1 directly hydroxylates estrogens.

Reason: The complete PMID:11555828 abstract explicitly reports human cDNA-expressed CYP1B1-catalyzed estradiol 2-, 4- and 16-alpha-hydroxylation, with the highest 4-hydroxylation among the compared enzymes. This is performed estrogen metabolism. Full Methods/tables remain inaccessible; retain the positive curated assertion with that access limit, not an unsupported claim about native physiological flux.

Summary: Human CYP1B1 produces catechol estrogens.

Reason: The complete 12865317 abstract explicitly includes CYP1B1 among fifteen human P450 preparations and states that it forms catechol estrogens with 4-hydroxylated products predominating. Full original access was blocked, so quantitative CYP1B1 product ratios are not reconstructed from this abstract. Independent human product-resolved experiments in 23821647 corroborate the metabolic function.

Summary: Human CYP1B1 directly converts estradiol to hydroxylated estrogens.

Reason: In the inspected 23821647 reconstitution, the modified human enzyme with human POR produces both 2- and 4-hydroxyestradiol, with 4-hydroxylation favored under the stated conditions. Mouse and rat enzymes have different ratios and active-site mutants alter preference. This supports human estrogen metabolism without assigning all polymorphs, species or tissues the same quantitative flux.

Summary: The mouse estrogen assay supports transfer of the metabolic function.

Reason: The exact Q64429 IDA evidence includes 23821647 and agrees with independently measured human CYP1B1 estrogen turnover in the same study. The ortholog transfer concerns the capacity to metabolize estrogen, not the rodent preference for 2-hydroxylation; the human enzyme favors 4-hydroxylation in the compared reconstitution.

Summary: CYP1B1 restrains pericyte population expansion.

Reason: Mouse Cyp1b1-null retinal pericytes expand more rapidly despite no increase in EdU incorporation; reduced apoptosis contributes to that difference. The performed cell-population assay supports the broad negative-regulation term, without equating population expansion with a direct cell-cycle block.

Summary: CYP1B1 restrains pericyte population expansion.

Reason: Mouse Cyp1b1-null retinal pericytes expand more rapidly despite no increase in EdU incorporation; reduced apoptosis contributes to that difference. The performed cell-population assay supports the broad negative-regulation term, without equating population expansion with a direct cell-cycle block.

Summary: The valid phylogenetic inference agrees with direct steroid hydroxylation.

Reason: The literal GO:0008395 IBD at PTN008400367 lies on the Q16678 path in the actual current PTHR24299 tree, whose target MSA reconstructs all 543 residues. Its descendant evidence includes human CYP enzymes and rodent/fish CYP1 proteins; the current IBD additionally lists a zebrafish source absent from the historical GOA list. Human CYP1B1 steroid hydroxylation is independently demonstrated in 23821647 and reported in the complete 10426814/11555828 abstracts. A target appearing among the descendant evidence is legitimate experimental grounding. No exact evolutionary date or identical substrate preference across all descendants is inferred. This activity class is retained as the available representation of the independently measured estradiol C4-hydroxylation reaction, RHEA:47280, pending resolution of the specific proposed GO term. Accepted estrogen 2-hydroxylase activity alone does not represent that distinct C4 product. By contrast, retained estrogen metabolism already entails the broad steroid-metabolism process, explaining the TOO_GENERAL process actions without treating ancestor breadth as additional evidence.

Summary: The matched electronic rule agrees with direct steroid hydroxylation.

Reason: ARBA00026772 matches the actual human P450 features and taxonomic branch. Its broad steroid-hydroxylase output agrees with human CYP1B1 estradiol turnover and the reported testosterone/progesterone activities. It is not evidence for every steroid substrate, identical ortholog specificity or steroid biosynthesis. This activity class is retained as the available representation of the independently measured estradiol C4-hydroxylation reaction, RHEA:47280, pending resolution of the specific proposed GO term. Accepted estrogen 2-hydroxylase activity alone does not represent that distinct C4 product. By contrast, retained estrogen metabolism already entails the broad steroid-metabolism process, explaining the TOO_GENERAL process actions without treating ancestor breadth as additional evidence.

Summary: Human CYP1B1 forms 14,15-epoxyeicosatrienoate.

Reason: The human CYP1B1 chromatogram and Table 3 in PMID:15258110 identify 14,15-EET against an authentic standard; its fraction is 6.87 ± 0.72% of total products. The reaction is NADPH-supported in a POR reconstitution. This supports the GO regioisomer activity; the paper does not independently resolve product enantiomers. The official Q16678 reaction object maps literal RHEA:49860 to 14R,15S-EET; the direct Rhea page was inaccessible. The separately inspected 20972997 human Supersome experiment and Table 2 resolve enantiomers: 8R,9S predominates, both 11,12 enantiomers occur, and 14R,15S predominates. These assignments are not inferred from the earlier regioisomer-only experiment; absolute assignments use the chromatographic calibration procedure described in that paper.

Summary: Human CYP1B1 forms 11,12-epoxyeicosatrienoate.

Reason: Human CYP1B1 produces 11,12-EET, identified by authentic-standard retention and reported as 5.20 ± 1.11% in Table 3. Mouse 11,12-EET was undetected under the reported profiling conditions and must not substitute for the human result. Retain the existing regioisomer term; no stereochemical resolution is claimed from this paper. The separately inspected 20972997 human Supersome experiment and Table 2 resolve enantiomers: 8R,9S predominates, both 11,12 enantiomers occur, and 14R,15S predominates. These assignments are not inferred from the earlier regioisomer-only experiment; absolute assignments use the chromatographic calibration procedure described in that paper.

Summary: The specific oxidative intrinsic-apoptosis route is unresolved.

Reason: PMID:23568032 provides positive intrinsic-apoptosis context: Cyp1b1-null mouse pericytes have lower Bax and Bim expression and lower basal/staurosporine caspase-3/7 activity. Discussion explicitly proposes Bax/Bim loss as one explanation and increased Akt phosphorylation as another. The same cells have higher DHE-detected oxidative stress and lower viability after peroxide; NAC lowers the ROS signal, but the reported NAC experiment does not rescue an apoptotic endpoint or establish a ROS-to-Bax/Bim causal chain. Methods mention peroxide in the caspase protocol, while the reported Figure 3 comparison is basal/staurosporine and Figure 4 reports peroxide viability/ROS; Methods and Results also differ in peroxide viability dose. Thus the positive intrinsic machinery and redox observations remain insufficiently connected to resolve this specific oxidative-stress-induced intrinsic signaling route. The additional PMID:23979599 mouse trabecular-meshwork experiments directly show increased caspase-3/7 after peroxide or staurosporine in knockout cells, but do not independently identify the initiating intrinsic route. Retain UNDECIDED for this exact transfer while preserving both positive contexts; accessible full text does not eliminate biological uncertainty.

Summary: The specific oxidative intrinsic-apoptosis route is unresolved.

Reason: PMID:23568032 provides positive intrinsic-apoptosis context: Cyp1b1-null mouse pericytes have lower Bax and Bim expression and lower basal/staurosporine caspase-3/7 activity. Discussion explicitly proposes Bax/Bim loss as one explanation and increased Akt phosphorylation as another. The same cells have higher DHE-detected oxidative stress and lower viability after peroxide; NAC lowers the ROS signal, but the reported NAC experiment does not rescue an apoptotic endpoint or establish a ROS-to-Bax/Bim causal chain. Methods mention peroxide in the caspase protocol, while the reported Figure 3 comparison is basal/staurosporine and Figure 4 reports peroxide viability/ROS; Methods and Results also differ in peroxide viability dose. Thus the positive intrinsic machinery and redox observations remain insufficiently connected to resolve this specific oxidative-stress-induced intrinsic signaling route. The additional PMID:23979599 mouse trabecular-meshwork experiments directly show increased caspase-3/7 after peroxide or staurosporine in knockout cells, but do not independently identify the initiating intrinsic route. Retain UNDECIDED for this exact transfer while preserving both positive contexts; accessible full text does not eliminate biological uncertainty.

Summary: CYP1B1 directly metabolizes a biological toxin as well as synthetic toxicants.

Reason: The toxin IBD at PTN001210461 is on the actual target path. Several recovered descendant experiments concern DMBA or 7H-dibenzo[c,g]carbazole, which are xenobiotic toxicants and alone would not meet the current organism-produced-toxin definition. Independent human evidence in the complete 36442682 abstract directly measures CYP1B1-dependent aflatoxin B1 conversion to AFM1 by LC-MS. That fungal toxin supplies positive target grounding for the broad inherited term. The abstract does not identify the proposed genotoxic epoxide or establish in vivo dominance, and no full Methods are claimed.

Summary: CYP1B1 supports VEGF production in mouse pericytes.

Reason: The actual 23568032 pericyte study measures VEGF in conditioned medium and reports reduced production with Cyp1b1 loss. This is a contextual regulatory contribution inferred to the human ortholog; it does not assign VEGF synthesis chemistry or direct transcription-factor activity to CYP1B1.

Summary: CYP1B1 supports VEGF production in mouse pericytes.

Reason: The actual 23568032 pericyte study measures VEGF in conditioned medium and reports reduced production with Cyp1b1 loss. This is a contextual regulatory contribution inferred to the human ortholog; it does not assign VEGF synthesis chemistry or direct transcription-factor activity to CYP1B1.

Summary: The traced donor studies do not resolve lipid breakdown as a CYP1B1-performed process.

Reason: The exact Q64429 IMP records cite PMID:19005183 and PMID:23979599. The recovered trabecular-meshwork original measures HNE/lipid peroxidation, oxidative stress, matrix organization and antioxidant responses; these positive observations do not identify the CYP1B1-performed lipid-breakdown step. The earlier endothelial original remains inaccessible beyond its complete abstract, so its precise experimental support cannot be rejected from the accessible record. Independent arachidonate oxidation establishes lipid metabolism, but the saved GO:0019369 ancestry does not entail lipid catabolism; this is not proof that every CYP1B1 oxidation is noncatabolic. Retain uncertainty about this exact transferred breakdown process while preserving the positive fatty-acid chemistry and mouse phenotypes.

Summary: The traced donor studies do not resolve lipid breakdown as a CYP1B1-performed process.

Reason: The exact Q64429 IMP records cite PMID:19005183 and PMID:23979599. The recovered trabecular-meshwork original measures HNE/lipid peroxidation, oxidative stress, matrix organization and antioxidant responses; these positive observations do not identify the CYP1B1-performed lipid-breakdown step. The earlier endothelial original remains inaccessible beyond its complete abstract, so its precise experimental support cannot be rejected from the accessible record. Independent arachidonate oxidation establishes lipid metabolism, but the saved GO:0019369 ancestry does not entail lipid catabolism; this is not proof that every CYP1B1 oxidation is noncatabolic. Retain uncertainty about this exact transferred breakdown process while preserving the positive fatty-acid chemistry and mouse phenotypes.

Summary: The actual CYP1B1 contribution in the modeled sterol pathway is estrogen metabolism.

Reason: R-HSA-211976 reaches Q16678 through estradiol 4-hydroxylation event 211951. The current sterol definition specifically requires a steroid with a hydrocarbon side chain; an umbrella pathway name is not a measurement of CYP1B1 cholesterol/sterol turnover. Refine the modeled target contribution to the directly established estrogen metabolic process, preserving the original pathway citation.

Proposed replacements: estrogen metabolic process

Summary: Reduced-flavoprotein monooxygenase activity is more informative than the broad oxidoreductase class.

Reason: The broad paired-donor oxidoreductase assertion is sound, but CYP1B1 oxygenation uses electrons delivered by reduced POR. GO:0016712 captures that mechanism and the demonstrated steroid, retinoid and fatty-acid substrate range. The distinct hydroperoxide-dehydration activity is not being described by this refinement.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: CYP1B1 receives the immediate reducing equivalents from a flavoprotein partner.

Reason: The actual 211951 event models estradiol 4-hydroxylation and reaches the Q16678 enzyme. NADPH is the upstream reducing source, but the directly reconstituted human CYP1B1 system uses NADPH-cytochrome P450 reductase. GO:0016712 identifies the immediate reduced-flavoprotein donor rather than implying direct NAD(P)H binding/reduction by CYP1B1.

Proposed replacements: oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen

Summary: The human variant assays support flavoprotein-linked monooxygenation.

Reason: The complete PMID:10426814 abstract explicitly identifies human CYP1B1 variants coexpressed with human NADPH-P450 reductase and steroid hydroxylation. Independently recovered PMID:15258110 and PMID:10681376 Methods establish reduced-flavoprotein-supported oxygenation. The original PMID:10426814 full Methods remain unavailable; retain the positive source tuple with curator deference and no full-construct claim.

Summary: The human substrate-oxidation study supports flavoprotein-linked monooxygenation.

Reason: The complete 22888116 abstract directly reports CYP1B1-dependent coumarin O-deethylation and estradiol 4-hydroxylation. The original EXP donor-class annotation is retained with curator deference because the full Methods were not recovered, and the same class is independently established by human POR reconstitution in 23821647. No claim is made that the abstract alone specifies every electron-transfer component.

Summary: The catalytic IBD agrees with the human CYP1B1 electron-transfer mechanism.

Reason: The literal GO:0016712 IBD at PTN009090155 lies on the human path in the current 585-node PTHR24299 tree. Descendant experiments span CYP1 proteins, including direct human Q16678 assays; current IBD WITH/FROM and historical source lists are retained separately. The target MSA reconstructs the complete 543-residue sequence, and independent human POR reconstitution supports the transferred catalytic class. No donor-count or legitimate self-source objection is made.

Summary: The human polymorphism study demonstrates CYP1B1 catalytic activity.

Reason: The complete 10871058 abstract reports recombinant human CYP1B1 variant preparations and measured ethoxyresorufin activity. It supports an active monooxygenase rather than a sequence-only prediction. The full original was not recovered; retain the established flavoprotein-linked class with curator deference and independent POR-reconstitution corroboration, without assigning every assay to the canonical 543-residue product.

Summary: The combined rule, ortholog and reaction evidence agrees with the flavoprotein-linked mechanism.

Reason: ARBA00027735 matches the actual target features; RHEA:17149 is an official Q16678 reaction with reduced NADPH-hemoprotein reductase as donor, and the exact Q64429 experimental records include 23821647 and 9367523. The latter uses an engineered mouse N terminus, whereas 23821647 also independently assays human CYP1B1. These sources support catalytic capacity without requiring identical human/mouse substrate preferences. Direct Rhea retrieval was blocked; the literal Rhea cross-reference was checked against the official UniProt reaction.

Summary: Human CYP1B1 directly transforms arachidonic acid.

Reason: Purified modified human CYP1B1 directly converts arachidonate into HETEs and EETs with NADPH/POR. Table 3 gives 54.46% midchain HETEs, 21.63% terminal HETEs and 23.57% epoxides. These are catalytic pathway steps, not a necessity-only phenotype. The experiment does not establish dominance over other enzymes in a human tissue or a specific downstream inflammatory/vascular role.

Summary: Mouse and human experiments support arachidonate metabolism.

Reason: The exact mouse Q64429 IDA record traces to 15258110, which also directly assays modified human CYP1B1 and human Supersomes. Both enzymes transform arachidonate, but the mouse enzyme has greater total EET contribution and different regioselectivity. The transfer retains the broad metabolic capacity rather than substituting mouse percentages for human ones.

Summary: CYP1B1 performs arachidonate epoxidation steps in the modeled pathway.

Reason: The actual Reactome pathway contains four EET-forming child events whose catalyst-set routes reach Q16678. Human enzyme experiments in 15258110 and 20972997 directly establish EET formation. CYP1B1 supplies the epoxidation steps; subsequent epoxide-hydrolase production of DHETs is not assigned to CYP1B1.

Summary: The engineered human CYP1B1 structure contains its catalytic heme.

Reason: The 2.7-angstrom human CYP1B1–ANF crystal structure contains the heme cofactor (Table 1 and structure discussion). The construct replaces residues 1–50, carries retained A119S and His4, so this establishes the CYP1B1 catalytic-domain cofactor without claiming an intact canonical 543-aa structure.

Summary: The matched P450 domains and conserved ligand support heme binding.

Reason: The InterPro-derived heme-binding assertion is independently consistent with the authentic human CYP1B1 structure and official Cys 470 axial-ligand annotation. Heme binding is part of the catalytic apparatus rather than a separate core binding role.

Summary: CYP1B1 supports collagen-fibril organization in the trabecular meshwork.

Reason: The exact Q64429 IMP record is grounded in 23979599 mouse tissue/cell experiments: Cyp1b1 loss changes collagen architecture, periostin expression and oxidative stress, and antioxidant intervention improves the matrix phenotype. This is a contextual contribution to matrix organization, with periostin-dependent extracellular assembly distinguished from CYP1B1 catalysis. It does not make CYP1B1 a collagen-processing enzyme or establish the responsible endogenous substrate.

Summary: CYP1B1 supports collagen-fibril organization in the trabecular meshwork.

Reason: The exact Q64429 IMP record is grounded in 23979599 mouse tissue/cell experiments: Cyp1b1 loss changes collagen architecture, periostin expression and oxidative stress, and antioxidant intervention improves the matrix phenotype. This is a contextual contribution to matrix organization, with periostin-dependent extracellular assembly distinguished from CYP1B1 catalysis. It does not make CYP1B1 a collagen-processing enzyme or establish the responsible endogenous substrate.

Summary: CYP1B1 restrains migration in the tested pericyte context.

Reason: The original mouse pericyte perturbation assays in 23568032 support increased migration after Cyp1b1 loss. Retain that context-specific regulatory sign while distinguishing the opposite endothelial migration phenotype in 20032512. Neither result implies a universal direction across cell types.

Summary: CYP1B1 restrains migration in the tested pericyte context.

Reason: The original mouse pericyte perturbation assays in 23568032 support increased migration after Cyp1b1 loss. Retain that context-specific regulatory sign while distinguishing the opposite endothelial migration phenotype in 20032512. Neither result implies a universal direction across cell types.

Summary: CYP1B1 limits integrin-associated matrix adhesion in mouse pericytes.

Reason: The actual 23568032 ECM-adhesion assays and integrin profiling support the curator’s negative-regulation interpretation. The observed association is contextual and does not prove CYP1B1 directly binds or inhibits an integrin receptor. The human assertion remains an ortholog transfer from mouse pericytes.

Summary: CYP1B1 limits integrin-associated matrix adhesion in mouse pericytes.

Reason: The actual 23568032 ECM-adhesion assays and integrin profiling support the curator’s negative-regulation interpretation. The observed association is contextual and does not prove CYP1B1 directly binds or inhibits an integrin receptor. The human assertion remains an ortholog transfer from mouse pericytes.

Summary: The primary-alcohol category adds no distinct function beyond retinol metabolism.

Reason: ARBA00029060 matches the actual target features. Retinol is a primary alcohol and the current typed ancestry places the accepted retinol metabolic process under this term. Direct retinol-to-retinal chemistry already supplies the informative substrate-level coverage; the broader chemical category remains true.

Summary: CYP1B1 participates in oxidative xenobiotic degradation pathways.

Reason: The actual xenobiotic-catabolic IBD at PTN001210461 is on the target path, with literal rat Cyp1a1 and human CYP1A2 descendant sources. The current human CYP1A2 source includes direct caffeine demethylation in 18619574. Independently, human CYP1B1 performs coumarin O-deethylation in 22888116, while mouse DMBA metabolism in 10051580 shows direct production of hydroxylated and dihydrodiol products. Retain this oxidative catabolic role without claiming complete mineralization, universal detoxification or absence of reactive products.

Summary: The hormone-metabolism category is already represented by estrogen and retinoid metabolism.

Reason: The matched ARBA00028011 rule is biologically consistent, and current typed ancestry places accepted estrogen and retinol metabolic processes beneath hormone metabolic process. The broad output adds no distinct endocrine-regulatory mechanism or new reaction beyond the directly supported substrate-specific metabolism.

Summary: Human CYP1B1 oxidizes retinol to retinal.

Reason: The original PMID:10681376 Methods and Figure 6/Table 3 show human CYP1B1 Supersomes converting all-trans-retinol to retinal with NADPH, human POR and cytochrome b5. The apparent Km is 11 micromolar and Vmax 493 pmol/min/nmol. The authors’ proposed extrahepatic physiological importance is distinct from this direct catalytic participation, which supports the existing process term.

Summary: Human CYP1B1 directly metabolizes retinol.

Reason: The recovered PMID:15258110 original directly shows human CYP1B1 retinol-to-retinal turnover in a reconstituted system, with an NADPH-minus comparison and authenticated product retention/spectral characteristics. Human apparent Km 18.5 micromolar and kcat 0.15/min differ strongly from the mouse ortholog. Retain metabolism without declaring CYP1B1 the principal in-vivo retinoic-acid synthesis route.

Summary: The ortholog transfer agrees with directly measured human retinol oxidation.

Reason: The exact Q64429 IDA record points to 15258110, which tests mouse and human CYP1B1, and independent human Supersome experiments in 10681376 measure retinol conversion to retinal. Preserve the combined orthology/UniPathway source and distinguish enzymatic capacity from dominance over other retinol-oxidizing enzymes in vivo.

Summary: Human CYP1B1 oxidizes retinal in a reconstituted enzyme assay.

Reason: The recovered PMID:15258110 original directly shows human CYP1B1 retinal-to-retinoate turnover, with apparent Km 8.5 micromolar and kcat 0.77/min. No retinoate oxidation was detected under the same assay design. The existing retinal metabolic process is supported; this is not evidence for a visual-pigment cycle function or dominant physiological retinoate supply.

Summary: Mouse retinal metabolism is corroborated by the human enzyme in the same study.

Reason: The exact Q64429 IDA record in 15258110 supports retinal conversion, and the study independently assays human CYP1B1. The transfer therefore agrees with positive human biochemistry. It does not identify which retinoid reaction explains glaucoma or establish retinal-homeostasis flux in a human tissue.

Summary: CYP1B1 promotes apoptotic responsiveness in the studied pericytes.

Reason: The original 23568032 basal/staurosporine caspase measurements support reduced apoptosis in Cyp1b1-null pericytes. Retain the broad positive-regulatory role while leaving the separate oxidative intrinsic-pathway specificity unresolved; no direct mitochondrial CYP1B1 substrate is identified.

Summary: CYP1B1 promotes apoptotic responsiveness in the studied pericytes.

Reason: The original 23568032 basal/staurosporine caspase measurements support reduced apoptosis in Cyp1b1-null pericytes. Retain the broad positive-regulatory role while leaving the separate oxidative intrinsic-pathway specificity unresolved; no direct mitochondrial CYP1B1 substrate is identified.

Summary: CYP1B1 supports endothelial-cell migration in the studied vascular context.

Reason: The actual Q64429 donor records include 19005183 and 20032512. The complete latter original measures migration and capillary morphogenesis under chronic knockout/siRNA and rescue conditions, linking the phenotype to oxidative stress, thrombospondin-2 and eNOS/NO availability. Acute CYP1B1 restoration does not fully rescue migration, and the earlier source remains abstract-only. Retain the contextual endothelial contribution without a direct cytoskeletal-motor or NO-synthase claim.

Summary: CYP1B1 supports angiogenic behavior in mouse endothelial and retinal assays.

Reason: The exact Q64429 IMP record in 20032512 is supported by actual endothelial capillary-morphogenesis assays and retinal vascular experiments, with eNOS/NO and oxidative-stress rescue analyses. The protein contributes to the studied regulatory setting; it is not itself a vessel-building structural protein or an NO synthase. The human assertion is an ortholog inference, not a human angiogenesis experiment.

Summary: CYP1B1 supports angiogenic behavior in mouse endothelial and retinal assays.

Reason: The exact Q64429 IMP record in 20032512 is supported by actual endothelial capillary-morphogenesis assays and retinal vascular experiments, with eNOS/NO and oxidative-stress rescue analyses. The protein contributes to the studied regulatory setting; it is not itself a vessel-building structural protein or an NO synthase. The human assertion is an ortholog inference, not a human angiogenesis experiment.

Summary: The donor study supports STAT3-associated signaling but not the specific receptor/JAK route.

Reason: The exact mouse Q64429 donor record traces to PMID:23568032. Figure 10 and Discussion report reduced STAT3 Ser727 phosphorylation and VEGF production in Cyp1b1-null retinal pericytes. These are positive signaling measurements, but the inspected experiments do not establish receptor activation or JAK dependence. Ser727 alone is not a diagnostic readout of that route; it also does not prove that JAK signaling is absent. The specific receptor/JAK-STAT assertion therefore exceeds the measured pathway resolution and is MARK_AS_OVER_ANNOTATED. The separate retained GO:0010575 assertions represent the positive VEGF-production context. This source-scoping judgment does not reject the donor identity, the phosphorylation result or all possible JAK involvement.

Summary: The donor study supports STAT3-associated signaling but not the specific receptor/JAK route.

Reason: The exact mouse Q64429 donor record traces to PMID:23568032. Figure 10 and Discussion report reduced STAT3 Ser727 phosphorylation and VEGF production in Cyp1b1-null retinal pericytes. These are positive signaling measurements, but the inspected experiments do not establish receptor activation or JAK dependence. Ser727 alone is not a diagnostic readout of that route; it also does not prove that JAK signaling is absent. The specific receptor/JAK-STAT assertion therefore exceeds the measured pathway resolution and is MARK_AS_OVER_ANNOTATED. The separate retained GO:0010575 assertions represent the positive VEGF-production context. This source-scoping judgment does not reject the donor identity, the phosphorylation result or all possible JAK involvement.

Summary: CYP1B1 affects vessel-forming behavior through pericyte–endothelial interactions.

Reason: The performed 23568032 endothelial–pericyte coculture morphogenesis experiment supports a contextual contribution of mouse pericyte Cyp1b1. This is distinct from a purified enzyme reaction or a human vessel-formation assay, and the human term is retained as ortholog inference.

Summary: CYP1B1 affects vessel-forming behavior through pericyte–endothelial interactions.

Reason: The performed 23568032 endothelial–pericyte coculture morphogenesis experiment supports a contextual contribution of mouse pericyte Cyp1b1. This is distinct from a purified enzyme reaction or a human vessel-formation assay, and the human term is retained as ortholog inference.

Summary: The human enzyme has testosterone 6-beta-hydroxylase activity.

Reason: The complete PMID:10426814 abstract explicitly reports kinetic effects of human CYP1B1 variants on testosterone 6-beta-hydroxylation. Retain the experimentally curated catalytic activity with explicit curator deference because the full Methods/table could not be recovered. No rate ranking, canonical-allele equivalence, endocrine dominance or physiological testosterone-control claim is inferred.

Summary: The official reaction mapping supports testosterone 6-beta hydroxylation.

Reason: The literal RHEA:46296 maps the same testosterone 6-beta-hydroxylation reaction named by GO:0050649 and the official CYP1B1 catalytic record. The positive PMID:10426814 abstract corroborates reaction capability; it does not establish that this is the dominant human steroid reaction. Direct Rhea page access failed; the inspected mapping is the official UniProt reaction object.

Summary: CYP1B1 contributes to retinal vascular morphogenesis in the studied mouse context.

Reason: The traced Q64429 IMP evidence in 20032512 includes retinal whole-mount vascular measurements and endothelial perturbation/rescue experiments. These support contextual developmental involvement, while chronic/acute differences and altered NO bioavailability limit a single-step mechanistic interpretation. Retain the human ortholog inference without inferring direct CYP1B1 nitric-oxide chemistry.

Summary: CYP1B1 contributes to retinal vascular morphogenesis in the studied mouse context.

Reason: The traced Q64429 IMP evidence in 20032512 includes retinal whole-mount vascular measurements and endothelial perturbation/rescue experiments. These support contextual developmental involvement, while chronic/acute differences and altered NO bioavailability limit a single-step mechanistic interpretation. Retain the human ortholog inference without inferring direct CYP1B1 nitric-oxide chemistry.

Summary: CYP1B1 affects cellular responses to peroxide challenge.

Reason: The exact Q64429 IMP record in 23979599 is supported by performed peroxide-challenge viability/oxidative-stress experiments, with complementary human TM1 knockdown assays. This is functional stress-response evidence, not merely increased gene expression. It does not establish a peroxide-detoxifying catalytic reaction or the specific intrinsic-apoptosis pathway assigned in separate rows.

Summary: CYP1B1 affects cellular responses to peroxide challenge.

Reason: The exact Q64429 IMP record in 23979599 is supported by performed peroxide-challenge viability/oxidative-stress experiments, with complementary human TM1 knockdown assays. This is functional stress-response evidence, not merely increased gene expression. It does not establish a peroxide-detoxifying catalytic reaction or the specific intrinsic-apoptosis pathway assigned in separate rows.

Summary: CYP1B1 contributes to the modeled terminal arachidonate-hydroxylation pathway.

Reason: The actual Reactome pathway reaches Q16678 through its terminal-HETE catalyst sets. Human 15258110 assays detect terminal products, including a 20-HETE standard-matched peak with possible 19-HETE coelution and a combined 16/17/18-HETE peak. Retain participation in this broader pathway as secondary to the enzyme’s better-resolved midchain/epoxygenase chemistry, without treating each modeled terminal product as an independently quantified human regioisomer.

Summary: The curated human assay supports estrogen 16-alpha hydroxylation.

Reason: The complete PMID:11555828 abstract explicitly reports a lesser but positive CYP1B1 contribution to estradiol 16-alpha-hydroxylation. A smaller contribution than CYP1A2/CYP3A4/CYP1A1 is not absence of catalysis. Retain the source-positive activity with the full-text access limit; do not transfer the reported pooled-liver rates to CYP1B1 alone.

Summary: Human CYP1B1 supports estrogen 2-hydroxylation.

Reason: The complete PMID:10426814 abstract reports estradiol 2-hydroxylation Vmax 0.3–0.6 nmol/min/nmol across four human CYP1B1 variant combinations, alongside greater 4-hydroxylation. This directly supports the existing catalytic claim; full assay tables/constructs remain unverified, and these variants are not separate official splice products.

Summary: Human CYP1B1 supports estrogen 2-hydroxylation.

Reason: The complete PMID:11555828 abstract explicitly includes positive estradiol 2-hydroxylation by cDNA-expressed human CYP1B1. Retain the curated activity despite lower activity than CYP1A2/CYP1A1 in that comparison, while acknowledging that original Methods/table and exact construct were not recovered.

Summary: The curated estrogen 2-hydroxylase activity agrees with the available human evidence.

Reason: The full 12865317 paper was not accessible, but its complete abstract states that CYP1B1 forms catechol estrogens with 4-hydroxylation predominant. Retain the curator’s positive 2-hydroxylase assertion with explicit access limits: independent product-resolved human assays in 23821647 directly demonstrate the minor 2-hydroxylation activity. No quantitative 2-hydroxylation value is attributed to the unread original.

Summary: Human estrogen 2-hydroxylation is established, with this paper-specific assay scope deferred to the curator.

Reason: The complete available 22888116 abstract describes estradiol 4-hydroxylation but does not report the 2-hydroxylation assay; its full original remained inaccessible. Absence from that abstract does not contradict the experimental curation. Retain the positive function with curator deference and independent human 2-hydroxyestradiol measurement in 23821647, while keeping the exact 22888116 2-hydroxylation source claim unverified at full-text scope.

Summary: The human reconstitution directly measures estradiol 2-hydroxylation.

Reason: The inspected 23821647 human-enzyme experiment measures 2-hydroxyestradiol as a positive, smaller product alongside predominant 4-hydroxyestradiol. Mutagenesis and human/rodent comparisons address regioselectivity; they do not negate the smaller human 2-hydroxylation capacity or establish equal physiological contributions.

Summary: The literal estradiol and estrone reactions support estrogen 2-hydroxylation.

Reason: The official Rhea-linked CYP1B1 record covers estrogen 2-hydroxylation for estrone and estradiol, consistent with the positive human variant abstract PMID:10426814 and estradiol comparison PMID:11555828. Retain the chemical capability without replacing more prominent 4-hydroxylation biology or claiming all CYP1B1 alleles have identical kinetics.

Summary: Human CYP1B1 has a directly measured secondary hydroperoxide-dehydration activity.

Reason: Actual PMID:21068195 Methods entry 23 and Table 2 assay CYP1B1 microsomes and report 5-, 12- and 15-HpETE conversion to the corresponding oxoETEs without added NADPH. Human CYP1B1 turnover is 11.8, 6.0 and 11.2/min, respectively. This fits hydroperoxy-icosatetraenoate dehydration and is not a CYP2S1-only result. The microsomes contained POR; no POR-removal or anaerobic test for CYP1B1 was reported, and physiological dominance is unestablished. This is a directly measured secondary catalytic mode; its contribution to oxo-lipid flux in intact human tissues is not established by the microsomal turnover assay, so it is retained without a separate dominant physiological core. KEEP_AS_NON_CORE retains this measured chemistry while distinguishing it from the three principal substrate-context cores. The target Table 2 cells and assay limits are transcribed with public original locators in CYP1B1-primary-source-notes.md; the paper, not that authored navigation, supplies the evidence.

Summary: Human CYP1B1 forms 8,9-epoxyeicosatrienoate.

Reason: Human CYP1B1 generates 8,9-EET identified against the authentic regioisomer standard, reported as 4.91 ± 0.35% of total products in PMID:15258110 Table 3. This supports the existing NADPH-dependent epoxygenase term. Retain the literal Rhea accession while distinguishing the paper’s regioisomer resolution from unmeasured enantiomeric specificity. The separately inspected 20972997 human Supersome experiment and Table 2 resolve enantiomers: 8R,9S predominates, both 11,12 enantiomers occur, and 14R,15S predominates. These assignments are not inferred from the earlier regioisomer-only experiment; absolute assignments use the chromatographic calibration procedure described in that paper. The human Table 3 column and the separate chiral Table 2 row are transcribed with public original URLs and units in CYP1B1-primary-source-notes.md; this is source navigation rather than an additional independent assay.

Summary: The olefinic-compound category is already covered by specific substrate metabolism.

Reason: The literal ARBA00033535 branches match the authenticated target features. Current typed ancestry places accepted arachidonate, retinol and retinal metabolic processes beneath olefinic compound metabolic process. Retain the truth of the chemical category while avoiding a redundant broad functional assertion.

Summary: CYP1B1 regulates oxidative-stress balance in the studied cells.

Reason: The exact Q64429 IMP record cites 19005183, whose complete abstract reports elevated oxidative stress and antioxidant rescue after Cyp1b1 loss. The independently recovered 23979599 and 20032512 originals add direct ROS/redox and perturbation/rescue measurements in trabecular and endothelial contexts. This supports regulatory involvement but not a universal antioxidant effect or a direct ROS-removal reaction catalyzed by CYP1B1.

Summary: CYP1B1 regulates oxidative-stress balance in the studied cells.

Reason: The exact Q64429 IMP record cites 19005183, whose complete abstract reports elevated oxidative stress and antioxidant rescue after Cyp1b1 loss. The independently recovered 23979599 and 20032512 originals add direct ROS/redox and perturbation/rescue measurements in trabecular and endothelial contexts. This supports regulatory involvement but not a universal antioxidant effect or a direct ROS-removal reaction catalyzed by CYP1B1.