## ARNT
- **UniProt:** P27540 · **batch:** proteostasis-batch-2026-06-03 · **review status:** COMPLETE (Falcon DR present; large review)
- **PN placement:** `Ubiquitin Proteasome System|E3 ubiquitin and UBL ligases|Cul4A/Cul4B substrate adaptor|AHR / ARNT / TBL3 complex|PAS` ; **PN-node mapping:** subtype(PAS)/type(AHR/ARNT/TBL3)=no_mapping; group(Cul4A/Cul4B substrate adaptor)=mapped/ok GO:1990756 (ubiquitin-like ligase-substrate adaptor activity, new_to_goa); class=context_only GO:0061630; branch=no_mapping. PN refs: PMID:17392787, PMID:28416634. Auxiliary domain IPR000014 (PAS).
- **Consistency:** CONTRADICTION between PN placement and the gene's biology. Deep research, notes, review YAML all establish ARNT (HIF-1β) as a **nuclear bHLH-PAS transcription-factor dimerization partner** for AHR/HIF-α — not a CUL4 ligase substrate adaptor. The notes explicitly reject the GO:1990756 projection: the AHR/ARNT/TBL3 leaf nodes are themselves no_mapping in the UPS YAML, and no reviewed ARNT literature shows it recruiting substrates to a CUL4 ligase.
- **PN story / NEW pressure:** PN asserts a UPS substrate-adaptor MF (GO:1990756) absent from ARNT GOA and unsupported. GO:1990756 is a real term, but applying it to ARNT **over-reaches** — the AHR/ARNT/TBL3 association reflects ARNT's transcription-complex role, not ligase-adaptor activity. Review correctly declined to add it to proposed_new_terms/core_functions. **Conclude: over-reaches.** ARNT's true functions (TF activity GO:0000981, heterodimerization GO:0046982, AHR binding GO:0017162) are already captured.
- **Mapping strategy:** ARNT is a false-positive member of the Cul4 substrate-adaptor group (likely placed via the AHR-CUL4B literature where AHR, not ARNT, is the ligase component). The group→GO:1990756 mapping may be valid for genuine adaptors but must NOT propagate to ARNT. Recommend exempting ARNT from this group projection.
- **Evidence alignment:** PN cites PMID:17392787 and PMID:28416634 (AHR-associated CUL4B ligase / AHR-ARNT structure). These concern the AHR ligase context and the AHR-ARNT DRE complex, supporting ARNT as DNA-binding partner — not as a UPS adaptor. Review evidence (PMID:1317062, PMID:7539918, PMID:28396409) is TF-centric and divergent from the UPS framing.
- **Verdict:** PN UPS adaptor projection over-reaches and is correctly rejected in-review. **Recommended edits:** exempt ARNT from GO:1990756 group propagation at the mapping layer [MAP].