FANCB is an integral structural scaffold of the FANCL–FANCB–FAAP100 (BL100) module. Its contribution is to hold the repair-activating assembly together. FANCL and UBE2T perform ubiquitin transfer to FANCI–FANCD2; FANCB is not assigned their enzymatic activity. The existing interstrand cross-link repair role follows from structural participation in this machinery, not from treating FANCB as a nuclease, DNA polymerase or the substrate of an activating reaction.
In PMID:17396147(https://pubmed.ncbi.nlm.nih.gov/17396147/), human HEK293 mammalian hybrid assays support FANCB–FAAP100 association and FANCB-dependent FAAP100–FANCL association. Human HeLa tagged-FANCL purifications recover the stable module from both nuclear and cytosolic extracts (Results and Figure 2A–D; mammalian hybrid, fractionation and purification Methods). The actual Figure 2 pixels were inspected in the direct experimental assessment. The separate database assessment read the corresponding text and captions without independently inspecting pixels. These are cellular association and purified-complex experiments, not a purified binary binding measurement. The paper's DT40 FAAP100 knockout is a chicken experiment and must not become a human FANCB knockout result.
PMID:27986592(https://pubmed.ncbi.nlm.nih.gov/27986592/) independently reconstitutes human BL100 in Sf9 insect cells. Its assembled-module and FANCL-dropout Results, Figures 2/3, and crosslinking-MS Methods support FANCB's organizing position: the interface persists after FANCL dropout, and FANCB crosslinks to FANCL and FAAP100. The study did not demonstrate self-association of isolated FANCB. Its assembled-module architecture therefore does not prove an autonomous FANCB homodimer or one invariant cellular core stoichiometry. Human BL100 and the Xenopus ID2 reagents used in associated assays remain distinct. Selected main Methods/Results/Discussion were read; figure pixels and supplemental constructs were not independently inspected for this study.
The 2016 study used both negative-stain EM and BL100 cryo-EM (Figure 1D/E and the separately named sample-preparation/data-collection Methods). Cryo-EM classes resembled the negative-stain classes without improved resolution. The subunit-dropout analyses and ID2 reconstruction include negative-stain imaging; ID2 should not be described as a cryo-EM reconstruction. This mixed-method scope qualifies the historical Cryo-EM shorthand preserved in the reference notes. The conserved cryo-EM structure in PMID:31666700(https://pubmed.ncbi.nlm.nih.gov/31666700/) uses a Gallus gallus eight-subunit complex expressed in insect cells, with chicken ID2 ubiquitination reagents. Selected cloning, purification, ubiquitination Methods and Results were read. This supports the assembled structural role but is not a human preparation or a separate FANCB catalytic assay. The inherited structural quotations remain in their original positions with these species and assembly limits.
The current GO:0030674 usage comment directs protein-complex scaffolds to GO:0140378, whose definition concerns an integral component holding a complex together. This more specific representation fits the stable BL100 role. The original protein-binding source is retained and refined to scaffold activity; no new annotation was manufactured to fill a core-function slot.
PMID:20347428(https://pubmed.ncbi.nlm.nih.gov/20347428/) explicitly identifies FANCB in human HeLa nuclear FANCM immunoprecipitates by mass spectrometry and immunoblotting (initial Results and Figure 1). Main Methods and captions were read, without supplementary Methods or figure pixels. This is evidence for membership in the FA nuclear complex. FANCM/MHF DNA-remodeling activities and the total cellular pools of those proteins are not assigned to FANCB.
PMID:22343915(https://pubmed.ncbi.nlm.nih.gov/22343915/) provides positive FANCB membership evidence in HeLa S3 tandem nuclear purifications (initial Results and actual Figure 1A/B pixels) and in FAAP20 immunoprecipitates (supplementary Figure S1C). The authentic supplement is publicly available through BioStudies S-EPMC3321854; all extracted supplemental Methods, figure labels and captions were read, and Figure S1 pixels were inspected. The chromatin-loading Results and Figure 5H label FANCA, FANCG and FAAP20 with H2A control. The supplemental fractionation Methods cite a prior protocol. No FANCB-labelled chromatin readout was identified in the inspected material, so the distinct imported FANCB chromatin assertion remains unresolved. Positive membership is preserved; incomplete target-specific localization evidence is not treated as proof that FANCB never associates with chromatin. The inherited FANCA quotation remains historical source context.
Ten Reactome contexts explicitly place human Q8NB91 residues 1–859 in nucleoplasm through the target's own entity 419528, not merely a parent event's compartment: core assembly, ID2/UBE2T recruitment, monoubiquitination, nuclease recruitment, unhooking, POLN recruitment, synthesis, deubiquitination, ATR recruitment and phosphorylation. These are supported pathway models, not ten independent microscopy experiments. Complex membership is recorded separately from anatomical location. The encompassing nucleus assertion remains valid and is not replaced by an exclusive nucleoplasm claim; nucleoplasm excludes chromosomes and nucleolus.
R-HSA-9835411 contains a distinct cytosolic FANCB entity 420791 within a FA-core:HSP70 assembly. The actual PMID:15299030(https://pubmed.ncbi.nlm.nih.gov/15299030/) abstract emphasizes FANCA/FANCC/FANCG and PKR responses; complete operative Methods were not recovered. This does not establish either a FANCB-specific PKR mechanism or the absence of FANCB from the experiment. Independently positive human cytosolic BL100 recovery is retained as a contextual location, without declaring that pool inactive.
Official PANTHER PTHR28450 version-19 tree/MSA data place exact human Q8NB91/859-residue target PTN002523840 below ancestral node PTN002408105. Four actual IBD assertions occur on this path, without a relevant NOT. The complex-membership self-WITH source is valid experimental grounding. The three regulatory assertions derive from mouse Fancb MGI:2448558/Q5XJY6, with current experimental donor annotations citing PMID:25520194(https://pubmed.ncbi.nlm.nih.gov/25520194/). The IBA method is documented in GO_REF:0000033.
Selected main Methods/Results/Discussion and Figures 1–6 captions of PMID:25520194 were read. Fancb exon-2 deletion was combined with Recql5 deletion or a strong Blm hypomorph in mouse embryonic stem cells; chromosome, nascent-strand, RAD51, restart and iPOND endpoints depend on lesion and genetic background. The proposed remodeling mechanism is speculative. PMID:21458466(https://pubmed.ncbi.nlm.nih.gov/21458466/) independently measures spontaneous sister-chromatid exchange, gene targeting, MMC response and foci in mouse embryonic stem cells. These studies support conserved contextual repair regulation, not FANCB recombinase, helicase or nuclease chemistry. The positive-repair and SCE contexts remain non-core; negative regulation of HR is unresolved for the reason below. Neither judgment rejects the verified ancestry or discounts a single experimental donor. No new mouse figure pixels or supplements were inspected.
The current UniProt Q8NB91 record describes an 859-residue protein without an alternative-products comment. Initiator-methionine removal and chain 2–859 are processing features. Separate RefSeq/Ensembl models and historical tagged or truncated constructs are not promoted to equivalent natural products. Exact current-sequence equivalence was not established for every historical reagent.
The original PMID:19965384(https://pubmed.ncbi.nlm.nih.gov/19965384/) supports replication-coupled ICL repair using Xenopus egg-extract ID2 depletion and add-back. All recovered main narrative and four figure captions were read; no supplement or pixels were inspected. It is pathway context, not a direct human FANCB incision assay. Human assembly evidence supplies independent target-role grounding. The founding FANCB paper and clinical variant study support X-linked disease context within their accessible abstract and selected introductory/discussion scope, without a new audit of all variants or a uniform variant mechanism.
Reference availability flags follow the immutable selected publication-cache metadata. External main/supplement availability and actual reading are described separately in each complete reference assessment. Thus abstract-only caches can coexist with inspected external originals; conversely PMID:32106311 carries full-text-available metadata but the saved extraction lacks operative Methods/Results. PMID:16116422 remains an inherited reference without a new scientific assessment here. The current PMID:32939280 assessment corrects its species and modeling scope as described below. Four shared reference assessments preserve both complete, separately labeled reading scopes, including the difference between actual pixel inspection and caption-only reading. Agent-authored notes summarize the current biological conclusions; provider failures are not replaced by fabricated research files.
PMID:25520194, Figure 7A/E and the Results subsection on damage-response factors at nascent DNA compares control mouse ES cells with Fancb exon-2 deletion, Recql5 deletion and the double mutant after mild or severe HU. FANCB loss reduces RAD51 recovered by iPOND; adding RECQL5 loss restores RAD51. The final Results paragraph and Discussion therefore assign RAD51 suppression in the FANCB-deficient background to RECQL5. They do not show that FANCB deletion elevates RAD51. Figures 2–6 independently support lesion-specific chromosome effects, nascent-strand protection and restart. Those positive results do not by themselves establish a reduction in the frequency, rate or extent of HR-mediated DSB repair by FANCB, as required by GO:2000042. That annotation remains UNDECIDED with intact source ancestry. The main text and captions were read; no new pixel inspection or supplement analysis is claimed.
The 2020 modeling study, PMID:32939280, uses the preceding chicken FA-core cryo-EM map and crosslinking data, with deep-learning predictions and Rosetta. See its Introduction, Methods on the prior map/models, and Results on full-complex modeling. It is not a new human structure; crosslinks used in model construction are not independent validation data. This corrects the inherited journal shorthand without changing any immutable source or quotation. The human BL100 dimer-of-trimers architecture remains supported independently by PMID:27986592 Results/Figures 2–3 and its human-protein/Sf9 Methods. No autonomous isolated FANCB homodimer or universal full-core stoichiometry follows from that assembly.
PMID:15502827(https://pubmed.ncbi.nlm.nih.gov/15502827/) explicitly establishes Xp22.31, X-inactivation and essential nuclear-core function in its accessible abstract. PMID:32106311(https://pubmed.ncbi.nlm.nih.gov/32106311/) supplies human clinical context for severe congenital abnormalities, including VACTERL-H, in the accessible abstract and Introduction; its cached extraction lacks operative Methods/Results. These scopes support the standalone disease summary, without a new variant-by-variant assessment or a measured dosage-response claim. The inherited quotes remain as historical anchors under the campaign preservation policy; claim-level evidence is recorded with references and public locators instead of new quotations.