ARPC1B: literature and annotation assessment

Structural role in a regulated actin-nucleating complex

The human platelet study identified p41-Arc by peptide sequencing and cDNA cloning, with clone 527050 listed in the Methods. Its Results distinguish p41-Arc from the previously identified human Sop2 homologue; the two are related proteins, not interchangeable names for the same experimental reagent. The p41/p40 bands yielded identical peptide maps, and their summed abundance supported a stoichiometric subunit of the seven-protein assembly. The paper reports “the seven polypeptide subunits of the complex are present in a 1:1:1:1:1:1:1 stoichiometry”. Its cellular imaging used other subunits, including Arp3, p34 and p21; this is complex-level localization, not direct ARPC1B immunofluorescence. PMID:9230079, original Methods and p41 Results.

The reconstitution paper provides complementary functional evidence: its complete abstract explicitly describes expression of the human seven-subunit complex in insect cells and distinct p41 effects on nucleation and stimulation. It assigns the strongest filament-binding role to p34/p20. Full original Methods were not recovered through the inspected publisher/author routes. The existing ARPC1B filament-binding annotation is therefore retained as a contribution within the complex, not an isolated p41 binding interface. The synthesized core omits a separate filament-binding edge because the inspected evidence does not resolve the ARPC1B interface; it retains the structural complex contribution and does not turn ARPC1B into an autonomous nucleator. PMID:11741539(https://doi.org/10.1016/S1097-2765(01)00393-8).

The complete isoform-comparison abstract reports faster actin assembly and altered network disassembly for ARPC1B/ARPC5L-containing complexes, with cortactin-dependent protection from coronin-mediated disassembly. Its original construct provenance and full Methods remain uninspected, so no reagent species is assigned from the title or later experiments. This supports functional diversity of assembled complexes, rather than intrinsic catalytic activity of ARPC1B. PMID:26655834(https://doi.org/10.1038/ncb3286).

Additional target-specific human cortical evidence was read in the original Results and captions of PMID:34673575, including patient-derived lymphoblastoid cells and Ramos cells. The recovered normal XML cache now permits direct, claim-specific attachments: Figure 3A places ARPC1B complexes at the actin cortex and shows decreased, irregular cortical F-actin in patient-derived cells; Figures 1 and 2 provide Ramos knockout and stimulated-polymerization corroboration. PMID:34673575, Figures 1–3 and target Results.

The inspected Methods explicitly identify human PBMC-derived primary B cells, patient EBV-transformed lymphoblastoid cells, and CRISPR-edited human Ramos cells. The pyrene assay combines rabbit-muscle actin, recombinant GST-VCA and cell lysates. Its loss of stimulation supports functional ARPC1B-containing machinery; it does not measure purified ARPC1B catalysis. Reciprocal cellular co-immunoprecipitation recovered more WASP with ARPC1B than ARPC1A under the tested conditions. This supports a differential partner association within cellular assemblies; it is not an isolated binary affinity measurement. The earlier external-reading note about an unresolved splenic subset is not used for a claim: no separate splenic experiment was identified in the inspected normal-cache text. Primary human B-cell provenance is now directly documented by the target Methods. This is a bounded Results/Methods read, not a complete supplement or figure-pixel audit. PMID:34673575, Cell preparation, cell lines, polymerization, co-IP and Study approval Methods.

Hematopoietic enrichment and human disease

The human patient study connects biallelic ARPC1B deficiency to congenital thrombocytopenia, abnormal platelet morphology and function, immunodeficiency and inflammatory disease. ARPC1B is enriched in hematopoietic cells and is a major ARPC1 isoform in platelets. This is enrichment rather than absolute restriction: the original discussion describes variable ARPC1A/B ratios across cells and tissues, and human ARPC1B staining is also available in nonhematopoietic cell lines. Deficient platelets show altered actin organization, spreading and proplatelet formation; these phenotypes support the structural actin-network role rather than separate newly proposed disease-process annotations. The complete abstract, selected target Results and Discussion were read, without a complete supplement or figure-pixel audit. PMID:28368018, human patient and platelet study.

LegK2 recognition: a specific interaction outside the core function

The original PMID:25944859 Figure 1 Results and vector/assay Methods resolve the human target. ARPC1B and ACTR3 constructs came from the human ORFeome resource, and ARPC1B was positive in binary yeast assays and affinity copurification from HEK293T cells. The latter result includes the literal passage “Flag-tagged ARPC1B (45 kDa), but not Flag-tagged ARP3, was copurified”. GST and LegK1 controls, plus continued ARPC1B binding to kinase-dead LegK2, distinguish the interaction from catalytic activity. The initial library bait showed residual self-activation despite 3-aminotriazole; that limitation is kept separate from the subsequent targeted tests. This is not a purified two-protein affinity measurement. Original Figure 1 and Methods.

The same paper's Figure 2 assay used purified Acanthamoeba Arp2/3 and recombinant LegK2 with phosphothreonine detection. That assay establishes the kinase's serine/threonine partner class; the human binding experiment is the distinct Figure 1 evidence. The more specific replacement is GO:0120283 protein serine/threonine kinase binding, whose official definition and GO:0019901 parent were checked. Only this child replacement is proposed. ARPC1B is the kinase-binding target, not the kinase, and this pathogen interaction is not a separate core function.

The canonical PMID:25944859 cache remains abstract-only. The target original-body reading used the independently recovered XML copy retained in quarantine during Seed12 auxiliary assessment; it did not overwrite the canonical source. The short original-body result above is linked to the published paper and is used through this notes file where the cache cannot validate a full-body quotation.

Location and propagation boundaries

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. The current gene table and antibody immunocytochemistry section were read directly; image pixels were not independently rescored. The cytosolic activity location also rests on cellular actin-complex function. These observations do not exclude a nuclear pool or assign every activity to cytosol. HPA gene table; HPA004832 antibody assessment.

All seven original Reactome summaries were read. They cover myosin-X-dependent extension, WASP/WAVE and N-WASP engagement, filament branching, myosin-associated internalization, and receptor-associated Leishmania uptake. Their complete nested ARPC1B participant/compartment graphs were not inspected. Each existing cytosol assertion is retained on independent human location/function evidence; none of those summaries is treated as direct ARPC1B imaging, myosin activity, or proof of a new receptor/pathogen process. Exact target mapping in those model references remains UNVERIFIED.

The nuclear paper's inspected Results distinguish all-seven-subunit chromatin proteomics in Xenopus egg extracts from human U2OS ChIP using Arpc2; confirmation by Western blot includes Arpc4. The precise human ARPC1B assignment and ARPC1A/B discrimination in the underlying proteomics record remain unresolved. Both existing nucleus assertions stay UNDECIDED. This does not allege a wrong-gene citation or exclude a nuclear pool. PMID:29925947, early Results and chromatin/cell Methods.

The exact ARPC1B protein/peptide assignment in the focal-adhesion study remains uninspected, despite reading its abstract and searching its available body. Its emphasis on beta-Pix is not evidence against a separate ARPC1B detection. The exosome study's complete abstract likewise does not resolve the target record. Both precise locations remain UNDECIDED and are omitted from the core activity location. PMID:21423176(https://doi.org/10.1038/ncb2216); PMID:20458337(https://doi.org/10.1038/icb.2010.64).

The rat O88656 donor is Arpc1b. PMID:25637714 reports estrogen/ER-beta-dependent Arpc1b transcript regulation in adult rat seminiferous-tubule culture and places Arpc1b near tubulobulbar structures. PMID:27113856 reports failed tubulobulbar-complex formation and sperm release, altered barrier/polarity markers and cell-cycle effects after rat Arpc1b knockdown. These are positive reproductive-cell observations, and a hormone response does not require ARPC1B to bind the hormone. The corresponding human tissue and isoform assignments remain unresolved. Hematopoietic enrichment neither establishes absence from human reproductive cells nor independently verifies the rat-to-human transfer. The estrogen, estradiol and tubulobulbar assertions remain UNDECIDED for that biological context, while exact donor-chain tracing is a separate unresolved question. Both complete official abstracts and bounded indexed rat Results/Discussion were read; the complete original Methods and figure pixels were not inspected. PMID:25637714(https://doi.org/10.1016/j.mce.2014.12.029); PMID:27113856(https://doi.org/10.1016/j.bbamcr.2016.04.022).

The current ontology places GO:0051015 actin filament binding under GO:0044877 protein-containing complex binding. The two original source relations differ: the human filament-binding row says contributes_to, whereas the rat-derived broad complex-binding row says enables. Retaining the curated contribution within Arp2/3 does not by itself settle the separate enables assignment. 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. An isolated binary assay is not a general prerequisite for the broad binding term. The donor-derived row therefore remains UNDECIDED without discarding the positive rat observation or the existing qualified human contribution. GO:0051015; GO:0044877; PMID:27113856(https://doi.org/10.1016/j.bbamcr.2016.04.022).

All three IBA annotations retain their actual seeded PANTHER:PTN000076207 node. No PAINT topology, MSA or IBD reconstruction is claimed. Independent target evidence supports the accepted functions while source tracing remains UNRESOLVED. Donor count and valid target-containing descendant evidence are not defects. The GO-CAM index search found no ARPC1B/O15143 entry. No NEW annotation is proposed, and the existing actin-nucleation and cortical-organization processes are combined in one structural core.

Source access

The normal PMID:25944859 cache remains abstract-only; its separately quarantined XML supplies the bounded original-body reading and short published-paper quotation described above. Normal caches are not rewritten to imply access they do not provide. PMID:11741539 and PMID:26655834 remain abstract-only, with their full original Methods unresolved. PMID:34673575 has normal XML text and supports the explicitly bounded human cell, lysate and co-immunoprecipitation readings. The additional three papers are attached using their own normal-cache availability and exact claim-specific passages; deeper reading, where stated, is separately attributed to the original publication.

One configured Falcon deep-research attempt failed during dependency preparation before provider execution and produced no provider report. The literature assessment here comes from manual primary reading. Every original GOA source object, qualifier, product representation, raw UniProt/GOA file and existing publication cache is preserved. The earlier notes are retained in the published baseline; the current synthesis has 25 ACCEPT, eight UNDECIDED, one MODIFY, no NEW and one structural core.