| Axis | Key molecular role | Key partners | Key PTMs/ubiquitin linkage/sites | Subcellular site | Representative 2021-2024 sources (with DOI URLs and year) |
|---|---|---|---|---|---|
| Autophagy initiation | Scaffold/regulator that promotes autophagy initiation by supporting the BECN1-PIK3C3/VPS34 complex, enabling ULK1 activation/stability, and relocalizing from dynein-associated pools to membranes required for autophagosome formation (pqac-00000000, pqac-00000001, pqac-00000004, pqac-00000006) | BECN1, PIK3C3/VPS34, ULK1, TRAF6, TRIM32, ERLIN1, WIPI1, CANX, GD3, cardiolipin (pqac-00000000, pqac-00000001, pqac-00000004, pqac-00000006) | K63-linked ubiquitination of ULK1 and BECN1; ULK1 phosphorylation of AMBRA1 at S465/S635; MTORC1 phosphorylation at S52 suppresses activity; AMBRA1 can be turned over by CRL4 and RNF2 during prolonged stress (pqac-00000001, pqac-00000004, pqac-00000006, pqac-00000009) | ER, ER-mitochondria contact sites/MAMs, lipid raft microdomains, microtubule/dynein-associated cytosol (pqac-00000004, pqac-00000006, pqac-00000009) | Manganelli et al., 2021, *Autophagy*, https://doi.org/10.1080/15548627.2020.1834207; Di Rienzo et al., 2024, *Autophagy*, https://doi.org/10.1080/15548627.2024.2389474 (pqac-00000004, pqac-00000009) |
| Mitophagy | Acts as a mitophagy scaffold/receptor, engaging LC3 through its C-terminal LIR and supporting PINK1-PRKN pathway activity by stabilizing PINK1 and cooperating with mitochondrial quality-control factors (pqac-00000000, pqac-00000001, pqac-00000004, pqac-00000009) | LC3, PRKN/PARKIN, PINK1, ATAD3A, HUWE1, BCL2, ERLIN1 (pqac-00000000, pqac-00000001, pqac-00000004, pqac-00000009) | LIR at aa 1043-1052; CHUK/IKKα phosphorylation at S1043 promotes AMBRA1-LC3 interaction; HUWE1-mediated steps are linked to MFN2/MCL1 turnover; AMBRA1 itself is subject to degradative ubiquitination by RNF2/RhoBTB3 in broader regulatory literature summarized by reviews (pqac-00000000, pqac-00000001, pqac-00000004, pqac-00000009) | Outer mitochondrial membrane, mitochondria-associated membranes (MAMs), ER-mitochondria contact sites (pqac-00000001, pqac-00000004, pqac-00000009) | Di Rienzo et al., 2022, *Autophagy*, https://doi.org/10.1080/15548627.2021.1997052; Di Rienzo et al., 2024, *Autophagy*, https://doi.org/10.1080/15548627.2024.2389474 (pqac-00000000, pqac-00000009) |
| CRL4 E3 ligase / cell cycle | Functions as DCAF3, a CRL4 substrate receptor whose split WD40 domain binds DDB1 to recruit substrates such as D-type cyclins for ubiquitination, thereby restraining cell-cycle progression and linking AMBRA1 loss to cyclin accumulation and reduced CDK4/6 inhibitor sensitivity (pqac-00000002, pqac-00000003, pqac-00000008, pqac-00000012, pqac-00000013) | DDB1, CUL4A/B, RBX1, Cyclin D1/D2/D3, CDK4, PP2A, MYC (pqac-00000002, pqac-00000003, pqac-00000008, pqac-00000011, pqac-00000013) | DDB1-binding interface includes AMBRA1 residues 1-41; V10 and L13 are essential for DDB1 binding and cyclin ubiquitination, while W14R and H929A partially impair function; split WD40 domain formed by N- and C-terminal regions; PXP motifs at 275-281 and 1206-1212 bind PP2A (pqac-00000003, pqac-00000011, pqac-00000012, pqac-00000013, pqac-00000016) | Cytosol/nucleus-associated CRL4 machinery; structural complex resolved for DDB1-AMBRA1; cell-cycle phenotypes assayed in U2OS cells (pqac-00000011, pqac-00000012, pqac-00000013, pqac-00000016) | Simoneschi et al., 2021, *Nature*, https://doi.org/10.1038/s41586-021-03445-y; Liu et al., 2023, *Nature Communications*, https://doi.org/10.1038/s41467-023-43174-6 (pqac-00000008, pqac-00000011, pqac-00000012, pqac-00000013) |
| Signaling / non-autophagy | Promotes non-autophagic signaling outputs, including CRL4-AMBRA1-dependent nonproteolytic Smad4 polyubiquitylation that enhances TGFβ transcriptional responses; reviews also summarize roles in focal-adhesion signaling, nuclear transcriptional control, and c-MYC/PP2A regulation (pqac-00000000, pqac-00000004, pqac-00000010) | Smad4, DDB1, CUL4A, PP2A, MYC, PTK2/FAK, SRC, AKAP8, CDK9, ATF2 (pqac-00000000, pqac-00000004, pqac-00000010) | Nonproteolytic polyubiquitylation of Smad4; Smad4 K436 is functionally important because K436R weakens rescue of TGFβ reporter/target-gene responses; key effects reported with P < 0.001 in n = 3 experiments in the excerpted study (pqac-00000010) | Cytosol and nucleus; focal adhesions and cell cortex also reported in review summaries (pqac-00000004, pqac-00000010) | Liu et al., 2021, *Cancer Research*, https://doi.org/10.1158/0008-5472.CAN-21-0431; Di Rienzo et al., 2024, *Autophagy*, https://doi.org/10.1080/15548627.2024.2389474 (pqac-00000004, pqac-00000010) |


*Table: This table summarizes experimentally supported functions, partners, modifications, and localizations of human AMBRA1/Q9C0C7 across autophagy, mitophagy, CRL4-mediated cell-cycle control, and non-autophagic signaling. It emphasizes 2021-2024 sources and maps each claim to the available evidence contexts.*