| Process/Pathway | Proposed FBXL12 molecular role | Direct substrate(s) and ubiquitin linkage if known | Key experimental evidence (assays/models) | Subcellular context | Publication (year, journal) and URL/DOI |
|---|---|---|---|---|---|
| Replication stress recovery / Fanconi anemia signaling / cancer cell survival | SCF^FBXL12 substrate receptor that recognizes chromatin-associated, CHK1-phosphorylated FANCD2 and promotes its proteasomal turnover to enable fork recovery | FANCD2; polyubiquitylation reported, linkage not specified in the extracted text; interaction with FANCI also detected | siRNA imaging screen; DNA fiber assays; neutral comet assays; co-IP; chromatin fractionation; CUL1 IP-MS; FBXL12 KO/rescue; MG132 rescue; FANCD2 phosphodegron analysis; viability assays in breast cancer cells | Primarily chromatin / replication forks; nuclear foci; chromatin-associated FANCD2 degradation | Brunner et al., 2023, *Molecular Cell* — https://doi.org/10.1016/j.molcel.2023.07.026 (pqac-00000000, pqac-00000001, pqac-00000003) |
| DNA double-strand break response / NHEJ factor removal | SCF-Fbxl12 adaptor recruiting Cul1-Skp1 complex to DSB-bound Ku for damage-induced ubiquitylation and removal from DNA | Ku80; heavily K48-linked polyubiquitylation reported in Xenopus extract system | Xenopus egg extract DNA-bead assays modeling DSBs; immunodepletion of Fbxl12/Cul1; dominant-negative Cul1; chromatin binding and release assays; F-box mutant analysis | DSB-associated chromatin; recruited in a Ku-dependent manner to DNA ends | Postow & Funabiki, 2013, *Cell Cycle* — https://doi.org/10.4161/cc.23408 (Xenopus mechanism; conservation to human FBXL12 inferred) (pqac-00000004, pqac-00000005, pqac-00000006) |
| G1 cell-cycle control / lung epithelial signaling | SCF^FBXL12 substrate receptor promoting ubiquitin-proteasome degradation of CaMKI, thereby reducing p27 phosphorylation, disrupting cyclin D1/CDK4 assembly, and inducing G1 arrest | CaMKI; polyubiquitylation shown; K59 identified as a critical acceptor site on CaMKI; linkage not specified | Co-IP and pull-down; CHX chase; MG132 sensitivity; in vivo and in vitro ubiquitylation with purified SCF components; CaMKI lysine mutants (K59R/K110R); BrdU/flow cytometry; immunostaining | FBXL12 and CaMKI co-localize mainly in cytoplasm; downstream effect includes nuclear retention/mislocalization of p27 | Mallampalli et al., 2013, *Cellular Signalling* — https://doi.org/10.1016/j.cellsig.2013.05.012 (pqac-00000016, pqac-00000017, pqac-00000018, pqac-00000021, pqac-00000022, pqac-00000023) |
| Trophoblast differentiation / placental development | SCF^FBXL12 substrate receptor driving ubiquitin-dependent degradation of ALDH3 to permit trophoblast stem-cell differentiation | ALDH3A1 and ALDH3A2; direct ubiquitylation shown in vitro and in cells; linkage not specified | Differential proteomics (DiPIUS/LC-MS/MS); reciprocal co-IP; in vivo and in vitro ubiquitylation; shRNA depletion; CHX chase; ALDEFLUOR activity assay; Fbxl12 knockout mice; TSC differentiation and gossypol rescue | Placental junctional zone; trophoblast stem/differentiating cells | Nishiyama et al., 2015, *STEM CELLS* — https://doi.org/10.1002/stem.2088 (pqac-00000009, pqac-00000010, pqac-00000011, pqac-00000012, pqac-00000013) |
| Thymocyte β-selection proliferation / pre-TCR and Notch signaling | SCF-Fbxl12 substrate receptor acting with SCF-Fbxl1 to degrade Cdkn1b/p27 downstream of pre-TCR and Notch-driven transcriptional induction | CDKN1B/p27; K48-linked polyubiquitylation; major ubiquitination site K165 | Conditional mouse knockout (Lck-Cre Fbxl12^fl/fl); anti-CD3 induction; OP9-DL1/DL4 cultures; HEK293T overexpression/ubiquitylation assays; MG132; genetic rescue by Cdkn1b deletion; cell-cycle profiling | DN/DP thymocytes; nuclear/cellular p27 turnover context in developing thymocytes | Zhao et al., 2019, *Nature Immunology* — https://doi.org/10.1038/s41590-019-0469-z (pqac-00000024, pqac-00000025, pqac-00000026, pqac-00000027, pqac-00000028, pqac-00000029, pqac-00000030) |
| Targeted protein degradation (TPD) platform potential | Candidate broad-acting proximity-dependent degrader when forcibly recruited to heterologous substrates; role here is application-oriented rather than endogenous biology | Not a defined endogenous substrate in this review excerpt; tested across 10 model substrates with different localizations | Human ORFeome/proximity-dependent (de)stabilization screens using eGFP-ABI1 reporter, anti-GFP nanobody or PYL1/ABI1 dimerization, eGFP/BFP ratio readout; focused ligase screen | Activity reported across substrates with varied subcellular localizations | Hermanns & Hofmann, 2024, *Signal Transduction and Targeted Therapy* — https://doi.org/10.1038/s41392-024-01884-3 (summarizing screen results that included FBXL12) (pqac-00000032) |
| General family annotation / baseline localization | F-box + leucine-rich repeat SCF substrate-recognition subunit; exact substrate spectrum still incomplete | Reported substrates/interactors across literature: ALDH3, Ku80, CaMKI, p21; linkage varies by substrate and is often unspecified in summaries | Review synthesis of primary studies | Cytoplasm and nucleus listed in review table | Tekcham et al., 2020, *Theranostics* — https://doi.org/10.7150/thno.42735 (pqac-00000002, pqac-00000007) |


*Table: This table summarizes the strongest published functional annotation evidence for human FBXL12, organized by pathway, substrate, mechanism, localization, and study. It is useful for quickly distinguishing well-supported endogenous roles from broader translational or screening-based observations.*