Cytochrome P450 71B1 is a heme-thiolate cytochrome P450 monooxygenase of field pennycress, a member of the CYP71 clan that dominates plant specialized (defense) metabolism. It was identified as a full-length cDNA cloned from Thlaspi arvense in 1994, but its substrate, catalyzed reaction, metabolic pathway, expression pattern, and subcellular localization have not been experimentally determined. Based on conserved P450 architecture it is predicted to catalyze NADPH- and O2-dependent oxidation of an organic substrate using a heme cofactor, with the heme iron coordinated by a conserved axial cysteine; like most plant P450s it is expected, but not shown, to be anchored to the endoplasmic reticulum membrane.
The preferred accession for this review is P49264. These relationships are manually assessed.
REFERENCE PROTEOME EQUIVALENT · Reviewed 2026-10-19
Reference proteome: UP000836841
Retain P49264 as the primary Swiss-Prot accession. The reference sequence is exactly identical across all 496 residues. Other P450 hits are substantially less similar. This supports equivalent protein representation without relying on the broad automatic cytochrome-P450 name to establish substrate specificity.
MMseqs2 searched 26,379 sequences across UP000836841 at E <= 1e-5 and sensitivity 7.5, returning 214 hits. Every returned sequence was globally aligned using BLOSUM62 with gap-open -10 and extension -0.5. Scores and sequences for all 214 returned candidates are retained, with 10 detailed alignment files. The heuristic search does not establish genomic absence or unique locus identity.
file:THLAR/CYP71B1/CYP71B1-record-evidence.yaml
target_sequence_count: 26379
file:THLAR/CYP71B1/CYP71B1-record-evidence.yaml
candidate_count: 214
A0AAU9RUE5: 496 identities across 496 global-alignment columns (100.0% identity including gaps), 0 substitutions and 0 gap columns. Query coverage is 100.0%; target coverage is 100.0%. Sequence similarity is interpreted in the manual rationale. Identity over paired residues is 100.0000% (496/496); gap columns are excluded from this denominator.
file:THLAR/CYP71B1/CYP71B1-record-evidence.yaml
query_length: 496 target_length: 496 alignment_columns: 496 identities: 496 mismatches: 0 gap_columns: 0 identity_percent: 100.0 query_coverage_percent: 100.0 target_coverage_percent: 100.0
The primary accession is outside every searched exact-taxon reference proteome. Current UniProt records place A0AAU9RUE5 in UP000836841 and give it the same taxon as the primary.
file:THLAR/CYP71B1/CYP71B1-record-evidence.yaml
primary_in_any_reference_proteome: false
file:THLAR/CYP71B1/CYP71B1-record-evidence.yaml
alternative_in_reference_proteome: true
file:THLAR/CYP71B1/CYP71B1-record-evidence.yaml
same_taxon: true
Sampled UniSave observations: 26-NOV-2014, entry version 68.: no Proteomes cross-reference; 07-OCT-2020, entry version 77.: no Proteomes cross-reference; 27-NOV-2024, entry version 86.: no Proteomes cross-reference. These dated observations do not establish uninterrupted membership/absence, the exact change date, or UniProt's motivation.
file:THLAR/CYP71B1/CYP71B1-record-evidence.yaml
entry_date: 26-NOV-2014, entry version 68. proteomes: []
file:THLAR/CYP71B1/CYP71B1-record-evidence.yaml
entry_date: 07-OCT-2020, entry version 77. proteomes: []
file:THLAR/CYP71B1/CYP71B1-record-evidence.yaml
entry_date: 27-NOV-2024, entry version 86. proteomes: []
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004497 monooxygenase activity | IEA GO_REF:0000002 | ACCEPT | Summary: Well-supported family-level inference. The protein has canonical cytochrome P450 domain architecture (Pfam PF00067), and plant P450s are heme-thiolate monooxygenases. The specific substrate and reaction are unknown, but monooxygenase activity is a sound conservative annotation. Supporting Evidence: file:THLAR/CYP71B1/CYP71B1-deep-research-falcon.md Plant cytochrome P450s are heme-thiolate monooxygenases that catalyze oxygenation reactions |
| GO:0005506 iron ion binding | IEA GO_REF:0000002 | ACCEPT | Summary: Correct. The P450 catalytic center binds an iron-containing heme; UniProt annotates an axial heme iron-binding residue at position 436. Iron ion binding is appropriate, captured more specifically by the heme binding annotation. Supporting Evidence: file:THLAR/CYP71B1/CYP71B1-deep-research-falcon.md a conserved cysteine coordinates the heme iron in the P450 catalytic center |
| GO:0016705 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen | IEA GO_REF:0000002 | ACCEPT | Summary: Correct and standard for a cytochrome P450 monooxygenase, which uses molecular oxygen with NADPH as the paired electron donor. Conservative family-level inference. Supporting Evidence: file:THLAR/CYP71B1/CYP71B1-deep-research-falcon.md RH + O2 + NADPH + H+ -> ROH + H2O + NADP+ |
| GO:0020037 heme binding | IEA GO_REF:0000002 | ACCEPT | Summary: Correct. Cytochrome P450s are heme-thiolate proteins; UniProt annotates the axial heme iron-binding residue (position 436). This is the most specific cofactor annotation and underpins the monooxygenase activity. Supporting Evidence: file:THLAR/CYP71B1/CYP71B1-deep-research-falcon.md P450s share a conserved catalytic center in which a conserved cysteine coordinates the heme iron |
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Download this section (compressed HTML)Q: What substrate(s) and reaction does Thlaspi arvense CYP71B1 catalyze, and in which pathway (e.g. glucosinolate, indole/camalexin-type, or other specialized metabolism) does it act?
Q: Is CYP71B1 anchored to the endoplasmic reticulum membrane, as is typical for CYP71-clan plant P450s?
Experiment: Heterologously express CYP71B1 (e.g. in yeast or N. benthamiana microsomes with a plant cytochrome P450 reductase) and screen candidate substrates from Brassicaceae specialized metabolism (indole/tryptophan-derived intermediates, glucosinolate precursors) by LC-MS to identify the catalyzed reaction.
Experiment: Determine subcellular localization with a fluorescent-protein fusion and test for an N-terminal ER membrane anchor.
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