All 18 imported contexts have reviewed decisions. This guide combines the accepted direct and database evidence assessments without expanding their original-access claims. Experimentally expressed human espin 3A, endogenous rodent espins and the two current 854- and 288-residue human products remain distinct. No activity is assigned to both natural products by default.
| Source | Original and operative locator | Read scope and interpretation |
|---|---|---|
| PMID:29572253 | Original PMC6232856, ESPN expression constructs, cell culture, inner-ear explant and actin-assay Methods; USH1M functional Results; Figures 4 and 5 | Actual main sections and captions read; Figure 4 and Figure 5 pixels inspected. Human espin 3A targets/elongates LLC-PK1-CL4 microvilli and mouse cochlear stereocilia. Purified His-human 3A binds rabbit F-actin at high-speed centrifugation and bundles it in the separate low-speed assay. Mutant/charge controls distinguish binding, targeting and bundling. The paper reports the 3A template as NM_031475 nucleotides 1777–2733; it is not automatically either current 854/288-aa human product. Supplements not inspected. |
| PMID:9763424 | Original PMC2132824, Materials and Methods; localization and recombinant binding Results; Figures 3–7, especially Figure 4 | Actual operative main/captions read; Figure 4 pixels inspected. Endogenous rat small espin localizes along brush-border microvillar actin bundles; rat small espin is 253 aa, with its own N-terminal sequence. Recombinant binding protein retains five extra residues after tag cleavage. The measured 50/150 nM values concern this rat reagent with human platelet/rabbit skeletal actin, respectively. No human ESPN affinity is inferred. |
| PMID:12598619 | Original PMC2854510, PCR/cloning, yeast two-hybrid and recombinant-protein Methods; PC isoform Results; Figures 5 and 7C/D; interaction Results | Actual selected Methods/Results/captions read from the accepted original capture. Rat PC espin variants bind a human IRSp53 186-aa SH3-containing GST fusion, with GST and espin proline-region deletion controls. Mouse IRSp53/Neuro-2a experiments are separate. No human ESPN assay or measured affinity constant for those PC constructs is established. No figure pixels or supplements inspected. |
| PMID:8799813 | Publisher original, PubMed identity and abstract | Actual original HTML/PDF requests returned 403; main text remains unread. The abstract positively reports rat espin at actin-rich plaques and a recombinant fragment's binding. F-actin annotations are retained using the independent inspected human and rat originals above, without claiming verification of this original experiment. |
The current official donor Q63618 is rat Espn and explicitly distinguishes small and Purkinje-cell products. The source human B1AK53 record declares the 854- and 288-aa products. The longer human sequence contains a proline-rich region; the shorter source product removes the long N-terminal region. This supports bounded interpretation of the gene-level SH3 ISS assertion without assigning all activities to every product.
A comparison of the official long sequences confirms a corresponding proline-rich segment (human residues 428–463; 33 identical columns in a 38-column gapped comparison with the rat sequence). Repeat-rich alignments can have alternatives. This is sequence-context support, not an affinity measurement, proof of exact identity to the historical PC reagent, or evidence that the human 288-aa product has SH3-binding activity.
Current definitions were checked for microvillus, brush border, SH3 domain binding, microvillar actin bundle assembly, filamentous actin, stereocilium and actin filament binding. Actin bundling supplies structural participation; it is not inferred solely from deafness or a perturbation phenotype.
This guide distinguishes experimentally expressed human espin 3A, endogenous rodent espins, and the two currently described natural human products. The 854- and 288-residue products are preserved separately; shared activity or localization is not inferred merely from their common gene.
| Assertion | Actual source and operative locator | Scope |
|---|---|---|
| Actin binding | InterPro IPR003124 and human match, WH2 residues 648–673 | WH2 is a monomer-binding domain. Human espin 3A filament binding is independently measured in PMID:29572253(https://pmc.ncbi.nlm.nih.gov/articles/PMC6232856/), Figure 5K; Figure 5L separately measures bundling. The WH2-derived annotation is refined to GO:0003785 actin monomer binding; separate source rows retain experimentally supported filament binding. No newly inspected WH2-only human assay is claimed. |
| Microvillus, stereocilium and actin-cytoskeleton localization | PMID:29572253(https://pmc.ncbi.nlm.nih.gov/articles/PMC6232856/), Materials and methods, Figures 4–5; PMID:9763424(https://pmc.ncbi.nlm.nih.gov/articles/PMC2132824/), Materials and methods and Figures 3–5 | Human GFP-espin 3A in LLC-PK1-CL4 epithelial cells and postnatal mouse cochlear explants; separate endogenous rat brush-border and recombinant rat small-espin evidence. The latter reagent is 253 residues, not the natural human 288-residue product. |
| Mouse Espn tip localization | PMID:26754646(https://pmc.ncbi.nlm.nih.gov/articles/PMC4738386/), Results section on targeting of espin-1 and MORN4, Figure 8A; Methods “Antibodies and immunostaining of whole-mount cochleas” | Endogenous espin-1 at P0 mouse inner- and outer-hair-cell stereocilium tips, in controls and myosin-III double mutants. Pan-espin labels shafts. The study does not establish that all isoforms are tip enriched or that myosin-III motors are universally required for localization. |
| Espn versus Espnl donor scope | PMID:26926603(https://pmc.ncbi.nlm.nih.gov/articles/PMC4773517/), Results “Localization of ESPNL in hair bundles” and “ESPNL binds but does not crosslink actin,” Figures 3–4; Methods “Antibodies,” “Expression plasmids,” and “Immunofluorescence and light microscopy” | Mouse Espn/espin-1 and Espnl are distinct. PB538 cross-reactivity with Espnl is acknowledged. Separate Espnl C-terminal antibodies and tagged mouse Espnl support its localization. Pan-espin shaft distribution is distinct from long-espin tip enrichment. Espnl actin-network targeting does not imply Espnl bundling or a human ESPN experiment. Main text and captions were inspected; figure pixels and supplements were not. |
No Reactome annotation occurs in this source lane. The exploratory PMID:16569662 main-text routes were unavailable; its experiments are not used as an inspected source. All original publication caches remain unchanged. The two additional mouse donor caches were acquired through the normal publication-fetch command.
The single core uses GO:7770064 actin-filament cross-linking activity. Current QuickGO and OLS identify a nonobsolete, unrestricted molecular function under cytoskeletal adaptor activity, describing linkage between actin filaments. OLS records creation on 16 April 2026. This is a specific measured molecular activity, not a generic protein-binding assertion. The core adds no NEW row to the imported annotation list.
In the human original, the ESPN expression-construct, cell-culture, inner-ear-explant and F-actin-assay Methods identify the reagents and hosts. Figure 5K and its accompanying Results measure binding by high-speed sedimentation; Figure 5L uses a separate low-speed assay to recover bundled actin. Wild-type human espin 3A supports bundling, whereas the six-residue deletion retains reduced filament binding but fails efficient bundling. Figures 4 and 5A–J distinguish projection targeting from elongation in epithelial cells and mouse cochlear explants. During core synthesis, these operative sections and captions were re-read and Figure 5 pixels were inspected again. The earlier direct assessment's Figure 4 access remains recorded unchanged; no additional supplements were inspected.
The rat small-espin original, Materials and Methods and Results/Figures 3–7, supplies complementary native brush-border localization, recombinant binding and bundling, and electron-microscopy descriptions of bundles. Core synthesis re-read the operative Methods, localization and biochemical Results and captions; it did not newly inspect the rat figure pixels. The earlier direct assessment's Figure 4 inspection is preserved. Rat 253-residue small espin and its binding constants are not attributed to the natural human 288-residue product. The tested human 3A template is likewise not equated with either natural human product.
Microvillar actin bundle assembly names work performed by the bundling protein, not merely a phenotype requiring it. Its broader parent, actin filament bundle assembly, is omitted from the same core. Microvillus and stereocilium are nonredundant cellular locations; the microvillar biological process is not asserted to occur in every sensory stereocilium. No stable protein-complex membership is inferred.
The mouse espin-1/myosin study, Results on espin-1 targeting, Figure 8A and antibody/immunostaining Methods, supports tip localization even in the tested myosin-III double-mutant setting. The Espn/Espnl study, localization Results, Figures 3–4 and antibody/expression Methods, separates pan-espin shaft labeling from espin-1-enriched tips and records PB538 cross-reactivity with Espnl. These main sections and captions were re-read; no mouse figure pixels or supplements were inspected. They constrain isoform and transport interpretations and do not establish universal myosin dependence or Espnl bundling. Rat PC-espin/IRSp53 binding remains a separate non-core observation; it is not a second ESPN core mechanism.
The human original Methods specify NM_031475 nucleotides 1777–2733 without an accession version. Official historical NM_031475.1 and NM_031475.2 both place the CDS at 169–2733. The reported interval therefore translates to 318 residues plus a stop, corresponding to protein residues 537–854. Version .2 matches the displayed human sequence; version .1 differs within that sequence. Current .3 has a 12-nucleotide upstream coordinate shift and must not be substituted into the historical coordinates silently.
The source-described 288-residue product removes canonical residues 1–536 and 543–572. Its official FASTA equals residues 537–542 joined to 573–854. It retains both WH2 and the disease-associated 790–795 region, supporting functional transfer at the gene level, but differs from the 318-residue interval by 30 residues. Thus neither a canonical-coordinate variant nor shared C-terminal modules identifies the tested plasmid as the 288-residue product. Exact historical plasmid identity remains limited by the omitted accession version. Repeated row-level product caveats were consolidated here and into focused questions; direct positive human evidence remains accepted.
Current official definitions confirm actin monomer binding as the specific WH2-domain inference and actin filament bundle as the structural assembly supported by localization and bundling. Filamentous actin denotes the actin polymer; it is no longer used as the proposed espin structural location. GO:7770064 is independently reconfirmed as an active molecular-function term. The original canonical strict-term validation passed; its absence from a partially populated committed cache is not evidence of an invalid identifier. Cross-linking remains in the core synthesis without manufacturing a NEW annotation or substituting it for the distinct WH2 monomer-binding inference.
No new supporting quotations are introduced under the explicit campaign instructions. All original normal source bytes and imported source fields remain exact. Falcon returned HTTP403 and the perplexity-lite fallback returned HTTP401 with insufficient quota during the real provider attempt; no provider report was generated. The notes and this source guide document the manual research and original-access limits. The proposed comparison experiment addresses a specific product distinction; a field-wide knowledge-gap claim is not inferred merely from a construct mapping limitation.