# TRIP4 (Q15650) research notes

## Summary
TRIP4 (Activating Signal Cointegrator 1, ASC-1; thyroid receptor-interacting protein 4) is a C4-type zinc-finger protein that functions in two distinct contexts. As a subunit of the ASC-1 / RQC-trigger (RQT) complex (with ASCC1, ASCC2 and the ASCC3 helicase), it acts in ribosome-associated quality control, where the complex recognizes K63-polyubiquitinated collided ribosomes and drives splitting/disassembly of the collided (disome) ribosomes so that the obstructing nascent chain can be targeted for degradation. Separately, TRIP4 acts as a nuclear transcriptional coactivator/cointegrator; through its zinc-finger transactivation domain it binds nuclear receptors (thyroid hormone receptor, estrogen receptor ESR1, androgen receptor), basal transcription factors (TBP, TFIIA), and coactivators (SRC-1/NCOA1, CBP/EP300), and potentiates nuclear-receptor-, SRF-, AP-1- and NF-kappaB-mediated transcription. Its coactivator activity is regulated by UFM1 modification (ufmylation); ligand-bound nuclear receptors displace the UFM1 protease UFSP2 from TRIP4, allowing ufmylation that promotes recruitment of EP300/NCOA1 and assembly of an active coactivator complex. TRIP4 is predominantly nuclear (cytoplasmic under serum deprivation; colocalizes with NEK6 at the centrosome). Biallelic loss-of-function variants in TRIP4 cause severe congenital neuromuscular disease (spinal muscular atrophy with congenital bone fractures, SMABF1; and congenital muscular dystrophy, Davignon-Chauveau type).

## Core functions (from review)
- **GO:0072344 rescue of stalled cytosolic ribosome** — Subunit of the ASC-1 / RQC-trigger (RQT) complex that resolves collided ribosomes during ribosome-associated quality control, recognizing K63-polyubiquitinated disomes and driving ribosomal subunit dissociation to rescue stalled ribosomes and initiate nascent-chain degradation.
- **GO:0003713 transcription coactivator activity** — Nuclear transcriptional coactivator/cointegrator that, via its C4-type zinc-finger transactivation domain, binds nuclear receptors (thyroid hormone, estrogen ESR1, androgen receptors), basal transcription factors and coactivators (SRC-1/NCOA1, CBP/EP300) to potentiate nuclear-receptor-, SRF-, AP-1- and NF-kappaB-mediated transcription; regulated by UFM1 modification.

## Provenance
Research and verbatim supporting quotes are recorded inline in `TRIP4-ai-review.yaml` (per-annotation `supported_by` and `references` findings). This notes file summarizes the completed review; see the YAML for evidence citations.