ARPC1B is the p41-Arc WD-repeat subunit of the seven-subunit Arp2/3 complex. It supports regulated branched actin-network assembly and cortical actin organization, including WASP-stimulated polymerization in human B cells. ARPC1B-containing complexes have distinct activation and disassembly properties from ARPC1A-containing complexes. ARPC1B is enriched in hematopoietic cells and is a major ARPC1 isoform in platelets. Biallelic loss causes immunodeficiency with inflammatory disease and congenital thrombocytopenia, with defects in platelet and immune-cell actin organization.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005200 structural constituent of cytoskeleton | IDA PMID:11741539 Reconstitution of human Arp2/3 complex reveals critical role... | ACCEPT | Summary: p41-Arc contributes structure and regulated activity within Arp2/3. Reason: PMID:11741539 reports reconstitution of the human complex and distinct contributions of p41 to nucleation and stimulation. Its complete abstract was read, but full original Methods were not recovered. Direct human platelet p41 isolation/stoichiometry in PMID:9230079 and independent human cellular actin-network evidence support the broad structural function. ACCEPT the established function without claiming a new complete read of the 2001 assays. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 p41, p21, and p16 contribute differently to nucleation and stimulation by ActA and WASP |
| GO:0005200 structural constituent of cytoskeleton | TAS PMID:9230079 The human Arp2/3 complex is composed of evolutionarily conse... | ACCEPT | Summary: Native human p41-Arc is a stoichiometric structural subunit. Reason: Actual PMID:9230079 Methods and Results identify p41-Arc from human platelet peptides, clone its cDNA and show stoichiometric incorporation in the seven-subunit complex. Later reconstitution and isoform studies place that subunit within the actin-nucleating machinery. The original localization images assay other subunits, so they are not represented as direct p41 imaging. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 p41, p21, and p16 contribute differently to nucleation and stimulation by ActA and WASP |
| GO:0005515 protein binding | IPI PMID:25944859 The Legionella Kinase LegK2 Targets the ARP2/3 Complex To In... | MODIFY | Summary: Human ARPC1B binds the bacterial serine/threonine kinase LegK2. Reason: The same-source human ORFeome constructs, binary yeast assays and positive HEK293T GST-LegK2/Flag-ARPC1B copurification support kinase recognition (PMID:25944859, Figure 1 and Methods). GST/LegK1 controls and kinase-dead LegK2 binding distinguish recognition from catalysis. Figure 2 phosphothreonine assays with purified Acanthamoeba complex establish the LegK2 partner class separately from the human binding assay. Refine to protein serine/threonine kinase binding, GO:0120283; this is not ARPC1B kinase activity or a core endogenous signaling role. The canonical cache is abstract-only, so the actual quarantined original-body result and its public locator are recorded in the linked notes. Proposed replacements: protein serine/threonine kinase binding Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md Flag-tagged ARPC1B (45Β kDa), but not Flag-tagged ARP3, was copurified file:human/ARPC1B/ARPC1B-notes.md The same paper's Figure 2 assay used purified Acanthamoeba Arp2/3 and recombinant LegK2 with phosphothreonine detection. PMID:25944859 LegK2 phosphorylates the ARPC1B and ARP3 subunits of the ARP2/3 complex. |
| GO:0005634 nucleus | EXP PMID:29925947 Nuclear ARP2/3 drives DNA break clustering for homology-dire... | UNDECIDED | Summary: Human nuclear isoform assignment remains unresolved. Reason: PMID:29925947 identifies all seven Arp2/3 subunits in Xenopus chromatin proteomics and uses Arpc2 antibodies for human U2OS chromatin immunoprecipitation. These establish nuclear complex behavior, but the inspected experiments do not distinguish a human ARPC1B-containing nuclear complex from an ARPC1A-containing one. Unlike cytosol, which has independent human ARPC1B HPA localization, no comparably resolved target observation was established here. Keep UNDECIDED without denying a nuclear pool or disputing the original experimental annotation. Supporting Evidence: PMID:29925947 We performed an unbiased proteomics screen to document the recruitment of proteins to chromosomal DSBs in cell-free S-phase extracts derived from Xenopus eggs. file:human/ARPC1B/ARPC1B-notes.md The precise human ARPC1B assignment and ARPC1A/B discrimination in the underlying proteomics record remain unresolved. |
| GO:0005634 nucleus | IEA GO_REF:0000044 | UNDECIDED | Summary: The nuclear mapping retains the source experimentβs isoform uncertainty. Reason: UniProt SL-0191 cites PMID:29925947 and maps to nucleus. The biological question is which human ARPC1 isoform occupies the nuclear complex: the inspected original experiments resolve Xenopus complex recruitment and human Arpc2, not that distinction. Independent human ARPC1B cytosol staining does not decide its nuclear distribution. UNDECIDED preserves the mapping while its target-specific nuclear basis remains unresolved. Supporting Evidence: PMID:29925947 We performed an unbiased proteomics screen to document the recruitment of proteins to chromosomal DSBs in cell-free S-phase extracts derived from Xenopus eggs. file:human/ARPC1B/ARPC1B-notes.md The precise human ARPC1B assignment and ARPC1A/B discrimination in the underlying proteomics record remain unresolved. |
| GO:0005829 cytosol | IDA GO_REF:0000052 | ACCEPT | Summary: Human staining and actin-complex evidence support a cytosolic pool. Reason: The current HPA gene subcellular table lists cytosol and vesicles in A-431, U-251MG and U2OS with Supported reliability. Its linked HPA004832 antibody page, however, rates immunocytochemistry Uncertain because the location does not agree with literature. These are differing assessments of the staining evidence, not uniformly strong validation. Retain the broad cytosol annotation on the combined human target staining and established cellular actin-complex biology, with that caveat. Image pixels were not independently rescored. A cytosolic pool does not exclude a nuclear pool or locate every ARPC1B activity. Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The HPA gene table lists cytosol and vesicles in A-431, U-251MG and U2OS as Supported, whereas the linked HPA004832 antibody page rates immunocytochemistry Uncertain for literature discordance; the broad cytosolic pool is retained on combined staining and cellular actin-complex evidence. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-1861595 | ACCEPT | Summary: Cytosol is independently supported in the myosin-X event context. Reason: R-HSA-1861595 describes myosin-X-driven pseudopod extension; its summary establishes the actin-rich event context, not ARPC1B motor activity or direct imaging. The broad cytosol assertion is retained because human ARPC1B is independently observed there by HPA. The nested ARPC1B participant and compartment assignments in this particular event were not reconstructed. Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The HPA gene table lists cytosol and vesicles in A-431, U-251MG and U2OS as Supported, whereas the linked HPA004832 antibody page rates immunocytochemistry Uncertain for literature discordance; the broad cytosolic pool is retained on combined staining and cellular actin-complex evidence. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-2029466 | ACCEPT | Summary: The branching event is compatible with an independently observed cytosolic pool. Reason: R-HSA-2029466 describes activated Arp2/3 engagement with a pre-existing actin filament and explicitly lists ARPC1 among the complex subunits. Human ARPC1B complex membership and HPA cytosol localization independently corroborate this broad compartment. The summary does not resolve ARPC1A versus ARPC1B in the nested event graph or establish an isolated ARPC1B filament-binding interface. Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The HPA gene table lists cytosol and vesicles in A-431, U-251MG and U2OS as Supported, whereas the linked HPA004832 antibody page rates immunocytochemistry Uncertain for literature discordance; the broad cytosolic pool is retained on combined staining and cellular actin-complex evidence. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-2029473 | ACCEPT | Summary: The filament-elongation context does not change the supported cytosol call. Reason: R-HSA-2029473 describes monomer addition to mother and daughter actin filaments during protrusion. This supplies pathway context, while the accepted ARPC1B cytosol location rests on direct human HPA data and its established actin-complex role. The event summary is not treated as a target-specific localization assay or proof of a distinct ARPC1B elongation activity; its nested participant graph remains uninspected. Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The HPA gene table lists cytosol and vesicles in A-431, U-251MG and U2OS as Supported, whereas the linked HPA004832 antibody page rates immunocytochemistry Uncertain for literature discordance; the broad cytosolic pool is retained on combined staining and cellular actin-complex evidence. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-2029476 | ACCEPT | Summary: The myosin-dependent internalization model is a contextual cytosol source. Reason: R-HSA-2029476 describes myosin contractility and phagosome formation. ARPC1B supplies actin-network machinery rather than the myosin motor function described in that summary. Independent human HPA evidence supports its cytosolic pool, so the existing location is retained; exact ARPC1B inclusion in this eventβs nested graph remains unverified. Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The HPA gene table lists cytosol and vesicles in A-431, U-251MG and U2OS as Supported, whereas the linked HPA004832 antibody page rates immunocytochemistry Uncertain for literature discordance; the broad cytosolic pool is retained on combined staining and cellular actin-complex evidence. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-2197690 | ACCEPT | Summary: WASP/WAVE release is compatible with the cytosolic actin-complex pool. Reason: R-HSA-2197690 describes dissociation of the branched junction from membrane-bound WASP/WAVE. The accepted location is supported independently by human ARPC1B cytosol staining and cortical actin-complex experiments, rather than an inference that ARPC1B performs the actin ATP-hydrolysis step in the summary. Exact target identity in the nested event graph has not been inspected. Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The HPA gene table lists cytosol and vesicles in A-431, U-251MG and U2OS as Supported, whereas the linked HPA004832 antibody page rates immunocytochemistry Uncertain for literature discordance; the broad cytosolic pool is retained on combined staining and cellular actin-complex evidence. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3928595 | ACCEPT | Summary: The N-WASP model provides complex context, with independent target location support. Reason: R-HSA-3928595 describes N-WASP VCA engagement of Arp2/3 and actin. This is consistent with a cytosolic actin assembly, and human HPA directly supports ARPC1B in cytosol. The eventβs neuronal context and generic ARP2/3 wording do not identify the ARPC1 isoform on their own; the exact nested graph remains unverified, and this CC call does not assign a new neuronal process. Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The HPA gene table lists cytosol and vesicles in A-431, U-251MG and U2OS as Supported, whereas the linked HPA004832 antibody page rates immunocytochemistry Uncertain for literature discordance; the broad cytosolic pool is retained on combined staining and cellular actin-complex evidence. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-9666458 | ACCEPT | Summary: The receptor-internalization model is retained as a contextual cytosol source. Reason: R-HSA-9666458 describes IgG-coated Leishmania uptake and actomyosin-dependent particle internalization. Its myosin-focused summary does not directly localize ARPC1B. Independent human target cytosol staining supports the existing broad CC assertion while this eventβs exact ARPC1B participant mapping remains uninspected; no pathogen-specific ARPC1B activity is inferred. Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The HPA gene table lists cytosol and vesicles in A-431, U-251MG and U2OS as Supported, whereas the linked HPA004832 antibody page rates immunocytochemistry Uncertain for literature discordance; the broad cytosolic pool is retained on combined staining and cellular actin-complex evidence. |
| GO:0005856 cytoskeleton | IEA GO_REF:0000044 | ACCEPT | Summary: The broad cytoskeletal location agrees with native assembly and cellular function. Reason: SL-0090 reflects the established actin-associated complex. Human platelet incorporation and human cellular cortical actin defects independently support cytoskeletal association. The broad electronic location is retained; it does not imply membership of every cytoskeletal assembly. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 p41, p21, and p16 contribute differently to nucleation and stimulation by ActA and WASP PMID:34673575 We found that ARPC1B complexes localized to the actin cortex of control LCL B cell lines and that lines derived from ARPC1B-deficient patients showed decreased and irregular cortical F-actin intensity (Figure 3A). |
| GO:0005885 Arp2/3 protein complex | IBA GO_REF:0000033 | ACCEPT | Summary: Human assembly corroborates inherited Arp2/3 membership. Reason: The exact inherited node is PANTHER:PTN000076207. Its tree/MSA/IBD placement has not been independently inspected, but human p41 complex isolation and reconstitution directly corroborate the asserted Arp2/3 membership. ACCEPT the biological claim and record the node trace as UNRESOLVED, rather than penalizing donor count or the valid self-containing descendant evidence. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000076207 UNRESOLVED Exact PAINT ancestral node copied from the seed; topology and IBD evidence not independently inspected. Target-specific functional corroboration is stated separately. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 reconstitution of active human Arp2/3 complex after expression of all seven subunits in insect cells. |
| GO:0005885 Arp2/3 protein complex | IDA PMID:11741539 Reconstitution of human Arp2/3 complex reveals critical role... | ACCEPT | Summary: Human reconstitution and native isolation support complex membership. Reason: The complete PMID:11741539 abstract explicitly describes human Arp2/3 reconstitution with p41 among the subunits. Human native platelet evidence independently closes broad membership. Full 2001 Methods remain unread; no exact uninspected construct or purification detail is asserted. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 reconstitution of active human Arp2/3 complex after expression of all seven subunits in insect cells. |
| GO:0005885 Arp2/3 protein complex | IEA GO_REF:0000120 | ACCEPT | Summary: The electronic complex prediction agrees with direct human evidence. Reason: The ARBA/IPR017383 assertion agrees with the observed human p41-Arc assembly in PMID:9230079 and reconstituted human complex in PMID:11741539. The rule conditions were not independently reconstructed; broad established membership is accepted on target evidence, not a family label alone. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 reconstitution of active human Arp2/3 complex after expression of all seven subunits in insect cells. |
| GO:0005885 Arp2/3 protein complex | IPI PMID:26655834 Isoform diversity in the Arp2/3 complex determines actin fil... | ACCEPT | Summary: ARPC1B-containing complexes have distinct actin-network behavior. Reason: The complete PMID:26655834 abstract compares ARPC1A- and ARPC1B-containing complexes and their assembly/disassembly behavior, directly supporting isoform-defined complex membership. Full original Methods were inaccessible. Native human p41 evidence independently corroborates the membership, and no uninspected original reagent species is invented. Supporting Evidence: PMID:26655834 Arp2/3 complexes containing ARPC1B and ARPC5L are significantly better at promoting actin assembly than those with ARPC1A and ARPC5, both in cells and in vitro. |
| GO:0005885 Arp2/3 protein complex | TAS PMID:9230079 The human Arp2/3 complex is composed of evolutionarily conse... | ACCEPT | Summary: Native human platelet purification establishes p41-Arc membership. Reason: Actual PMID:9230079 peptide sequencing, cDNA identification and native human platelet purification directly identify p41-Arc as a stoichiometric subunit. This supports the existing complex membership without requiring the other-subunit microscopy to have assayed ARPC1B. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 reconstitution of active human Arp2/3 complex after expression of all seven subunits in insect cells. |
| GO:0005925 focal adhesion | HDA PMID:21423176 Analysis of the myosin-II-responsive focal adhesion proteome... | UNDECIDED | Summary: The exact focal-adhesion protein assignment remains uninspected. Reason: PMID:21423176 is a focal-adhesion proteomics study, and its complete abstract and available article text were inspected for the target. The exact ARPC1B detection/peptide assignment underlying this HDA annotation remains uninspected. A Ξ²-Pix foreground does not make the annotation wrong-gene. Leave the precise focal-adhesion assertion UNDECIDED, rather than replacing it with general actin-cytoskeleton evidence. Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The exact ARPC1B protein/peptide assignment in the focal-adhesion study remains uninspected, despite reading its abstract and searching its available body. |
| GO:0015629 actin cytoskeleton | IEA GO_REF:0000002 | ACCEPT | Summary: Native assembly and cellular evidence support actin-cytoskeleton association. Reason: IPR017383 family assignment agrees with native human Arp2/3 membership and direct human cortical actin-network evidence. ACCEPT the broad actin-cytoskeleton location; exact InterPro rule tracing is not claimed. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 p41, p21, and p16 contribute differently to nucleation and stimulation by ActA and WASP PMID:34673575 We found that ARPC1B complexes localized to the actin cortex of control LCL B cell lines and that lines derived from ARPC1B-deficient patients showed decreased and irregular cortical F-actin intensity (Figure 3A). |
| GO:0015629 actin cytoskeleton | NAS PMID:26655834 Isoform diversity in the Arp2/3 complex determines actin fil... | ACCEPT | Summary: Complex dynamics corroborate actin-cytoskeleton association. Reason: PMID:26655834 establishes functional actin-network behavior of ARPC1B-containing complexes in its complete abstract. Its exact original localization Methods remain unread. The same broad actin-cytoskeleton association is independently corroborated by target-specific human cell experiments and native human assembly, so ACCEPT rather than treating a NAS code as a defect. Supporting Evidence: PMID:26655834 Arp2/3 complexes containing ARPC1B and ARPC5L are significantly better at promoting actin assembly than those with ARPC1A and ARPC5, both in cells and in vitro. PMID:34673575 We found that ARPC1B complexes localized to the actin cortex of control LCL B cell lines and that lines derived from ARPC1B-deficient patients showed decreased and irregular cortical F-actin intensity (Figure 3A). |
| GO:0015629 actin cytoskeleton | TAS PMID:9230079 The human Arp2/3 complex is composed of evolutionarily conse... | ACCEPT | Summary: Complex-level localization is supported without claiming p41-specific imaging. Reason: The original PMID:9230079 functional localization experiments use Arp3/p34/p21 and complex-level interpretation, not an ARPC1B-specific antibody. Its human p41 identification plus later target-specific human cortical evidence support the broad actin-cytoskeleton annotation, while that source boundary remains explicit. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 p41, p21, and p16 contribute differently to nucleation and stimulation by ActA and WASP PMID:34673575 We found that ARPC1B complexes localized to the actin cortex of control LCL B cell lines and that lines derived from ARPC1B-deficient patients showed decreased and irregular cortical F-actin intensity (Figure 3A). |
| GO:0030866 cortical actin cytoskeleton organization | IBA GO_REF:0000033 | ACCEPT | Summary: Human cortical evidence corroborates the inherited organization process. Reason: The exact IBA node PTN000076207 is not independently reconstructed. Human patient/Ramos ARPC1B data in PMID:34673575, whose target Results and Methods were read in both the publisher text and the recovered XML cache directly corroborate cortical actin-network organization, with deficient cortical structures and polymerization responses. This supports the existing inherited process assertion; the node source remains UNRESOLVED. No new B-cell signaling process is inferred. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000076207 UNRESOLVED Exact PAINT ancestral node copied from the seed; topology and IBD evidence not independently inspected. Target-specific functional corroboration is stated separately. Supporting Evidence: PMID:34673575 We found that ARPC1B complexes localized to the actin cortex of control LCL B cell lines and that lines derived from ARPC1B-deficient patients showed decreased and irregular cortical F-actin intensity (Figure 3A). PMID:34673575 Like LCLs, control Ramos cells also spontaneously formed lamellipodia in suspension, and these structures were entirely dependent on ARPC1B (Figure 1F). PMID:34673575 VCA-stimulated actin polymerization was completely abolished in all ARPC1B-deficient patient cell lines (Figure 2B) |
| GO:0032355 response to estradiol | IEA GO_REF:0000107 | UNDECIDED | Summary: Rat estradiol-responsive expression does not resolve the human reproductive context. Reason: PMID:25637714 reports estrogen-responsive Arpc1b transcription through ER-beta manipulation in adult rat seminiferous-tubule culture. That is positive response biology and does not require ARPC1B to bind hormone. Its conservation in the corresponding human reproductive cells remains unresolved: human hematopoietic enrichment does not establish absence elsewhere, and HPA detects ARPC1B in nonhematopoietic cell lines. Keep UNDECIDED for the human context rather than rejecting the rat observation or treating donor-chain access as the biological verdict. Propagation Review Root cause: UNRESOLVED Sources checked: UniProtKB:O88656 UNRESOLVED Rat Arpc1b identity established; exact donor row/assay chain and human-context transfer remain unverified. Supporting Evidence: PMID:25637714 We also find that the estrogen regulation of Arpc1b and Evl is mediated through estrogen receptor Ξ² |
| GO:0034314 Arp2/3 complex-mediated actin nucleation | IBA GO_REF:0000033 | ACCEPT | Summary: Target evidence corroborates inherited complex-mediated nucleation. Reason: Native human assembly, the human reconstitution abstract and ARPC1B-containing complex polymerization studies independently corroborate Arp2/3-mediated nucleation. PTN000076207 topology remains unread, but no target-specific loss contradicts its inferred function; self-containing descendant support is legitimate. Record source tracing as UNRESOLVED while accepting the function. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000076207 UNRESOLVED Exact PAINT ancestral node copied from the seed; topology and IBD evidence not independently inspected. Target-specific functional corroboration is stated separately. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 p41, p21, and p16 contribute differently to nucleation and stimulation by ActA and WASP |
| GO:0034314 Arp2/3 complex-mediated actin nucleation | IDA PMID:11741539 Reconstitution of human Arp2/3 complex reveals critical role... | ACCEPT | Summary: Human p41 contributes to nucleation in the reconstituted complex. Reason: The complete PMID:11741539 abstract explicitly assigns p41 a distinct role in nucleation and stimulation in a reconstituted human complex. This is direct participation of a subunit in the nucleating machinery, not merely a downstream loss phenotype. Original full Methods remain unavailable and are not reconstructed from later papers. Supporting Evidence: PMID:11741539 p41, p21, and p16 contribute differently to nucleation and stimulation by ActA and WASP |
| GO:0034314 Arp2/3 complex-mediated actin nucleation | IDA PMID:26655834 Isoform diversity in the Arp2/3 complex determines actin fil... | ACCEPT | Summary: ARPC1B-containing complexes promote actin assembly. Reason: The complete original PMID:26655834 abstract directly compares actin-assembly rates of ARPC1B-containing complexes. It supports the existing complex-mediated process, without claiming autonomous ARPC1B nucleation or re-reading inaccessible original Methods. Supporting Evidence: PMID:26655834 Arp2/3 complexes containing ARPC1B and ARPC5L are significantly better at promoting actin assembly than those with ARPC1A and ARPC5, both in cells and in vitro. |
| GO:0034314 Arp2/3 complex-mediated actin nucleation | IEA GO_REF:0000120 | ACCEPT | Summary: The electronic nucleation assertion agrees with functional complex evidence. Reason: The combined ARBA/IPR prediction agrees with target-specific human complex reconstitution and independent ARPC1B complex activity. ACCEPT the established process; exact ARBA condition evaluation was not independently reproduced. Supporting Evidence: PMID:9230079 the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry PMID:11741539 p41, p21, and p16 contribute differently to nucleation and stimulation by ActA and WASP |
| GO:0036284 tubulobulbar complex | IEA GO_REF:0000107 | UNDECIDED | Summary: The rat tubulobulbar observation leaves the human cell-context assignment open. Reason: PMIDs:25637714 and 27113856 place rat Arpc1b near tubulobulbar structures and associate knockdown with failed tubulobulbar-complex formation and sperm release. The human ARPC1B localization in the corresponding reproductive compartment has not been established by the inspected evidence. Hematopoietic enrichment alone does not contradict such a pool. UNDECIDED reflects that tissue- and isoform-specific uncertainty, not a claim that rat localization or the human structure is biologically impossible. Propagation Review Root cause: UNRESOLVED Sources checked: UniProtKB:O88656 UNRESOLVED Rat Arpc1b identity established; exact donor row/assay chain and human-context transfer remain unverified. Supporting Evidence: PMID:25637714 Localization of these proteins at or in the vicinity of tubulobulbar complexes reveals that ARPC1B, EVL, PICALM, EEA1 and STX5A seem to be involved in spermiation. PMID:27113856 Here, knockdown of Arpc1b by siRNA in adult rat testis led to defects in spermiation caused by failure in TBC formation. |
| GO:0043627 response to estrogen | IEA GO_REF:0000107 | UNDECIDED | Summary: Human transfer of the rat estrogen response remains unresolved. Reason: The original rat work connects estrogen/ER-beta perturbation to Arpc1b transcript regulation in seminiferous tubules (PMID:25637714); this supports the donor response without making ARPC1B an estrogen receptor. The known human immune-cell phenotypes neither demonstrate nor contradict the same regulation in human reproductive tissue. Keep UNDECIDED pending evidence for that human context, with exact donor tracing uncertainty recorded separately. Propagation Review Root cause: UNRESOLVED Sources checked: UniProtKB:O88656 UNRESOLVED Rat Arpc1b identity established; exact donor row/assay chain and human-context transfer remain unverified. Supporting Evidence: PMID:25637714 We also find that the estrogen regulation of Arpc1b and Evl is mediated through estrogen receptor Ξ² |
| GO:0044877 protein-containing complex binding | IEA GO_REF:0000107 | UNDECIDED | Summary: The exact enables complex-binding assignment remains unresolved. Reason: GO:0051015 actin filament binding is a child of GO:0044877 protein-containing complex binding, so filament binding is relevant to this broad term. The existing assertions differ in relation: this rat-derived row says enables, whereas the human filament-binding row explicitly says contributes_to. The accepted complex contribution does not by itself settle an enables assertion for ARPC1B. Targeted PMID:27113856 Results show altered recruitment of Arp2/3 components to actin after rat Arpc1b knockdown, but the exact donor annotation and corresponding human activity assignment remain unresolved. An isolated binary assay is not a general requirement for this broad binding term. Retain UNDECIDED for that source and relation uncertainty while preserving the qualified human contribution and positive rat observations. Propagation Review Root cause: UNRESOLVED Sources checked: UniProtKB:O88656 UNRESOLVED Rat Arpc1b identity established; exact donor row/assay chain and human-context transfer remain unverified. Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The inspected rat work measures altered recruitment of Arp2/3 components to actin after knockdown; the precise donor annotation and corresponding human activity remain unresolved. |
| GO:0051015 actin filament binding | IDA PMID:11741539 Reconstitution of human Arp2/3 complex reveals critical role... | ACCEPT | Summary: The established qualified filament-binding annotation is retained. Reason: The original annotation explicitly says contributes_to, so it concerns ARPC1B within Arp2/3 rather than isolated p41 affinity. PMID:11741539 describes reconstituted human complex activity and distinct p41 contributions, while its abstract assigns the strongest filament-binding role to p34/p20. The full original assay was not recovered. Retain the curated contribution on the combined complex evidence, without claiming a resolved ARPC1B-specific mother-filament contact. The author-synthesized core emphasizes the directly inspected WASP-responsive complex activity instead of elevating that unresolved interface. Supporting Evidence: PMID:11741539 p34/p20 bind actin filaments and likely function in actin branching. PMID:11741539 p41, p21, and p16 contribute differently to nucleation and stimulation by ActA and WASP |
| GO:0070062 extracellular exosome | HDA PMID:20458337 MHC class II-associated proteins in B-cell exosomes and pote... | KEEP AS NON CORE | Summary: Detected in an extracellular-vesicle proteome. The protein is plausible EV content, but this is not where it functions. Reason: Arp2/3 complex subunit. Cytosolic protein (UniProt); cytosolic proteins, including abundant enzymes and cytoskeletal proteins, are expected and often promiscuous EV contents (MISEV2018 (PMID:30637094) category 2b). True, but not its core location. (Manual re-review for OMICS_EVIDENCE, 2026-10-10; previous action: UNDECIDED.) Supporting Evidence: file:human/ARPC1B/ARPC1B-notes.md The exosome study's complete abstract likewise does not resolve the target record. |
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Download this section (compressed HTML)Q: Does the original human nuclear source resolve ARPC1B versus ARPC1A in its complete proteomics assignments?
Q: Does the exact rat complex-binding donor claim add evidence beyond qualified mother-filament engagement?
Q: Can the human 2001 p41-specific full Methods refine its contribution without overstating isolated binding?
Experiment: Resolve human ARPC1B versus ARPC1A peptides in the original nuclear and focal-adhesion datasets and confirm the corresponding endogenous pool with paralog-specific reagents.
Experiment: Compare intact and ARPC1B-depleted reconstituted complexes under matched assembly conditions to distinguish indirect structural support for mother-filament binding from an isolated ARPC1B interface.
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