| Aspect | Current best-supported conclusion | Key evidence (brief) | Representative primary sources (with year, journal) | URL/DOI |
|---|---|---|---|---|
| Identity / aliases | Human **ASCC1** encodes **activating signal cointegrator 1 complex subunit 1**, also known as **ASC-1 complex subunit p50**; it is a subunit of the ASC-1/ASCC complex rather than an independently validated catalytic repair enzyme. (pqac-00000022, pqac-00000006) | Original purification identified a steady-state ASC-1 complex from HeLa nuclei containing P200, P100, and **P50**; later DNA-damage work defines ASCC as containing **ASCC1, ASCC2, ASCC3** associated with ALKBH3. (pqac-00000022, pqac-00000004, pqac-00000006) | Jung et al., 2002, *Mol Cell Biol*; Soll et al., 2018, *J Biol Chem* | https://doi.org/10.1128/MCB.22.14.5203-5211.2002; https://doi.org/10.1074/jbc.RA117.000114 |
| Domain architecture (KH/HCH + 2H-PDE) | ASCC1 has an N-terminal **KH-like RNA-binding domain** that includes a newly defined **helix-clasp-helix (HCH)** nucleotide-binding motif, fused to a C-terminal **two-histidine phosphodiesterase (2H-PDE)/RNA ligase-like** domain with two HXT motifs. (pqac-00000005, pqac-00000048, pqac-00000037) | Crystal structures and SAXS in 2024 showed a compact KH–PDE arrangement with limited flexibility; the PDE forms a V-shaped channel with two HXT motifs and unusual active-site geometry. (pqac-00000005, pqac-00000032, pqac-00000033) | Chinnam et al., 2024, *J Biol Chem* | https://doi.org/10.1016/j.jbc.2024.107368 |
| Molecular activities: RNA binding specificity | Best-supported direct biochemical activity is **sequence-selective RNA binding**, with preference for **CGCG-containing RNA**; binding depends on the KH **GXXG** motif. (pqac-00000032, pqac-00000031) | EMSA with eight 12-nt RNAs found binding only to the CGCG-containing RNA under stringent salt; binding detectable at ~60 nM protein; GXXG→GDDG mutation abolished binding; corresponding DNA did not shift. (pqac-00000032, pqac-00000033) | Chinnam et al., 2024, *J Biol Chem* | https://doi.org/10.1016/j.jbc.2024.107368 |
| Molecular activities: PDE activity status | ASCC1’s C-terminal domain is structurally a **2H-PDE**, but **direct phosphodiesterase activity is not yet validated for the physiological substrate**; tested cleavage of 2-5A was negative, implying a different or regulated substrate. (pqac-00000032, pqac-00000035) | HPLC assays showed no detectable cleavage of 2-5A by human or *A. pompejana* ASCC1, while positive control VP3-CTD cleaved >95%; structural analysis still supports cyclic-phosphate chemistry potential. (pqac-00000032, pqac-00000034) | Chinnam et al., 2024, *J Biol Chem* | https://doi.org/10.1016/j.jbc.2024.107368 |
| Complex membership / partners | ASCC1 is a component of the **ASC-1/ASCC complex** with **ASCC2, ASCC3, and TRIP4/ASC-1**; in alkylation repair it functionally connects to the **ALKBH3–ASCC** pathway. Direct binding is strongest for **ASCC3**, which scaffolds ASCC1–ASCC2 association. (pqac-00000024, pqac-00000006, pqac-00000021) | Recombinant pulldown: His-ASCC3 binds GST-ASCC1; ASCC1 and ASCC2 do not bind each other directly; co-IPs show ASCC3 bridges ASCC1 with ASCC2. Kito et al. detected ASCC1, ASCC2, ASCC3, TRIP4 on scanning ribosomes. (pqac-00000024, pqac-00000006, pqac-00000021) | Soll et al., 2018, *J Biol Chem*; Kito et al., 2023, *EMBO J* | https://doi.org/10.1074/jbc.RA117.000114; https://doi.org/10.15252/embj.2022112869 |
| Subcellular localization and dynamics | ASCC1 is predominantly **nuclear**, localizes constitutively to **nuclear speckles** that overlap with **PRP8**, and **leaves these foci after alkylation damage**; unlike ASCC2/ASCC3, its basal speckle localization precedes damage. (pqac-00000006, pqac-00000024, pqac-00000030) | IF microscopy showed HA-ASCC1 in nuclear speckles before damage and reduced speckle localization after MMS; ASCC1 KO increases ASCC3 foci yet reduces ASCC2–ASCC3 co-localization, indicating a regulatory role in assembly/recruitment. (pqac-00000024, pqac-00000025, pqac-00000030) | Soll et al., 2018, *J Biol Chem* | https://doi.org/10.1074/jbc.RA117.000114 |
| Pathway: alkylation damage response | ASCC1 acts as a **regulatory/accessory factor** in the **ALKBH3–ASCC alkylation damage response**, helping proper recruitment/organization of ASCC2–ASCC3 at damaged sites rather than directly catalyzing dealkylation. (pqac-00000024, pqac-00000030, pqac-00000003) | ASCC1 KO causes **MMS hypersensitivity** and is **epistatic with ASCC3**; loss of ASCC1 increases ASCC3 foci but many lack ASCC2; HXT-motif/C-terminal mutants fail to rescue proper ASCC2–ASCC3 co-localization. (pqac-00000025, pqac-00000027, pqac-00000030) | Soll et al., 2018, *J Biol Chem*; Dango et al., 2011, *Mol Cell* (pathway context for ALKBH3-ASCC) | https://doi.org/10.1074/jbc.RA117.000114; https://doi.org/10.1016/j.molcel.2011.08.039 |
| Pathway: transcriptional coactivation | The strongest classical evidence supports ASCC1/P50 as a **transcriptional coactivator component** required for **AP-1** transactivation, within an ASC-1 complex that also stimulates **SRF** and **NF-κB** signaling. (pqac-00000022, pqac-00000023, pqac-00000009) | Anti-P50 microinjection nearly abolished TPA-induced AP-1 reporter activation; rescue occurred with WT P50 but not KH-mutant P50, arguing ASCC1 is functionally required in vivo for AP-1 transactivation. (pqac-00000023) | Jung et al., 2002, *Mol Cell Biol* | https://doi.org/10.1128/MCB.22.14.5203-5211.2002 |
| Pathway: ribosome quality control (RQC) | ASCC participates in mammalian RQC, but current evidence indicates **ASCC1 is dispensable for ribosome splitting/stall resolution in at least some cytoplasmic settings**, whereas **ASCC3 helicase** and likely **ASCC2 ubiquitin interactions** are the core required activities. (pqac-00000044, pqac-00000046, pqac-00000047) | 2024 NAR and prior review evidence state ASCC1 is essential for nuclear DNA-repair function but dispensable for stalled-ribosome dissociation; ASCC can split ubiquitinated queues, monosomes, and 48S complexes when mRNA overhang and ubiquitin requirements are met. (pqac-00000044, pqac-00000052) | Miścicka et al., 2024, *Nucleic Acids Res*; Meunier et al., 2021, *Int J Mol Sci* | https://doi.org/10.1093/nar/gkae087; https://doi.org/10.3390/ijms22116039 |
| Pathway: translation initiation / scanning | A 2023 advance suggests the ASC-1/ASCC complex also promotes **translation initiation by scanning ribosomes** on a subset of transcripts; ASCC1 is present in the scanning-ribosome-associated complex, although ASCC3 is the experimentally emphasized motor subunit. (pqac-00000021, pqac-00000052) | Sel-TCP-MS identified **ASCC1, ASCC2, ASCC3, and TRIP4** on eIF4A1-bound scanning ribosomes; ASCC3 knockdown impaired 43S loading/scanning dynamics and reduced translation efficiency for selected transcripts. (pqac-00000021) | Kito et al., 2023, *EMBO J* | https://doi.org/10.15252/embj.2022112869 |
| Human disease: SMABF2 | Biallelic loss-of-function **ASCC1** variants cause **SMABF2** (spinal muscular atrophy with congenital bone fractures 2), a severe congenital neuromuscular/bone fragility disorder. (pqac-00000010, pqac-00000054, pqac-00000057) | WES/WGS and cDNA studies identified nonsense, frameshift, splice, and deletion alleles; patient fibroblasts showed near-absent ASCC1; functional work supports impaired osteoblastogenesis and enhanced adipogenesis. (pqac-00000054, pqac-00000060) | Knierim et al., 2016, *Am J Hum Genet*; Rosano et al., 2021, *Am J Med Genet A*; Voraberger et al., 2023, *Front Endocrinol* | https://doi.org/10.1016/j.ajhg.2016.01.006; https://doi.org/10.1002/ajmg.a.62219; https://doi.org/10.3389/fendo.2023.1137573 |
| Cancer / prognostic biomarker data | ASCC1 is **not an established clinical biomarker**, but recent analyses suggest it may have **prognostic value**, especially in pancreatic cancer and some other tumor types; interpretation remains exploratory. (pqac-00000053, pqac-00000048) | TCGA analysis across ~7000 tumor samples found ASCC1 mRNA higher in tumors in 7/15 tumor types and lower in 3/15; in pancreatic adenocarcinoma, high ASCC1 expression associated with poorer survival with **hazard ratio ~3.7**. (pqac-00000048, pqac-00000053) | Chinnam et al., 2024, *J Biol Chem* | https://doi.org/10.1016/j.jbc.2024.107368 |
| Key quantitative statistics | Frequently cited current quantitative anchors: **CGCG RNA binding detectable at ~60 nM**; **2-5A cleavage undetectable** for ASCC1 in HPLC assay; **7/15** tumor types with higher ASCC1 expression; **PAAD HR ~3.7** for high ASCC1; **18 SMABF2 patients from 13 families** summarized in 2023 review context; in hMSCs, ASCC1 knockdown caused **>90% reduction in mineralization**, **~50% increase in adipogenesis**, **>40% reduction in SMAD3 phosphorylation**, and **>50% downregulation of RUNX2/SERPINF1**. (pqac-00000032, pqac-00000039, pqac-00000042, pqac-00000048) | These values come from biochemical EMSA/HPLC, TCGA survival/expression analysis, and disease-mechanism studies in patient cells/hMSCs. (pqac-00000032, pqac-00000039, pqac-00000048) | Chinnam et al., 2024, *J Biol Chem*; Voraberger et al., 2023, *Front Endocrinol* | https://doi.org/10.1016/j.jbc.2024.107368; https://doi.org/10.3389/fendo.2023.1137573 |


*Table: This table summarizes the best-supported functional annotation for human ASCC1 (UniProt Q8N9N2), including molecular function, complexes, pathways, disease relevance, and recent quantitative findings. It is designed as a concise evidence map for rapid reference in the full report.*