ANO10 (TMEM16K) is an integral membrane phospholipid scramblase that acts predominantly in the endoplasmic reticulum. It moves phospholipids between membrane leaflets, with activity modulated by calcium and membrane lipid composition. The protein also permits nonselective ion flux in reconstituted membranes, while surface localization and cellular currents vary with expression context. ANO10 supports endosomal trafficking through ER–endosome contacts, although the connection between lipid scrambling and sorting remains unresolved. Biallelic pathogenic variants cause autosomal recessive spinocerebellar ataxia.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005227 calcium-activated cation channel activity | IBA GO_REF:0000033 | UNDECIDED | Summary: The precise calcium-gated cation activity remains unresolved, including its phylogenetic basis. Reason: The exact PAINT IBD placement remains unresolved; target self-inclusion is valid descendant evidence. Human PMID:22946059 explicitly leaves direct cation permeation versus activation of a parallel conductance unresolved. Purified PMID:31477691 salt flux supports ion permeability without settling that cation-specific mechanism or its calcium gating. Propagation Review Root cause: UNRESOLVED Sources checked: PANTHER:PTN002642655 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:Q9NW15 UNRESOLVED Target self-inclusion is legitimate descendant experimental grounding, not circularity. The exact ancestral node and its inherited scope remain unresolved. Supporting Evidence: file:human/ANO10/ANO10-notes.md Its cation experiments leave direct ANO10 permeation versus activation of a separate conductance unresolved. PMID:31477691 determining whether a reconstituted protein dissipates a KCl gradient in the absence of ionophores |
| GO:0005227 calcium-activated cation channel activity | IDA PMID:22946059 Anoctamins are a family of Ca2+-activated Cl- channels. | UNDECIDED | Summary: Cellular cation conductance does not unambiguously identify ANO10 as the calcium-gated cation pore. Reason: The original human PMID:22946059 cation-substitution experiments allow ANO10 permeation or activation of a separate conductance. That unresolved cation attribution is the main distinction from the reported chloride currents. Purified salt flux does not settle the specific pore or gating claim; this experimental assertion is uncertain, not refuted. Supporting Evidence: file:human/ANO10/ANO10-notes.md Its cation experiments leave direct ANO10 permeation versus activation of a separate conductance unresolved. PMID:31477691 determining whether a reconstituted protein dissipates a KCl gradient in the absence of ionophores |
| GO:0005229 intracellularly calcium-gated chloride channel activity | IDA NOT PMID:21984732 The anoctamin family: TMEM16A and TMEM16B as calcium-activat... | UNDECIDED | Summary: The original negative channel assertion cannot yet be reconciled across the experimental contexts. Reason: The original publisher body is now accessible: PMID:21984732 includes negative TMEM16K iodide-quenching experiments despite its Symposium Report format. PMID:20056604 independently reports negative quenching/baseline effects but positive slow patch-clamp currents; PMID:22946059 reports positive stimulated currents. Preserve the source NOT and UNDECIDED because these conditions remain scientifically unreconciled, not because the body is unread. Supporting Evidence: PMID:21984732 Expression of other anoctamins is devoid of detectable channel activity. PMID:20056604 ANO9 and ANO10 suppressed baseline Cl(-) conductance PMID:20056604 Patch clamping of ANO-expressing FRT cells indicated that apart from ANO1 also ANO6 and 10 produced chloride currents, albeit with very different Ca(2+) sensitivity and activation time. file:human/ANO10/ANO10-notes.md The TMEM16K-negative iodide-quenching result is from ionomycin-stimulated transfected HEK293 cells. |
| GO:0005229 intracellularly calcium-gated chloride channel activity | IDA PMID:22946059 Anoctamins are a family of Ca2+-activated Cl- channels. | KEEP AS NON CORE | Summary: Calcium-associated chloride currents are retained as a conditional secondary capability. Reason: The human PMID:22946059 calcium-stimulation and anion-substitution experiments support the original conditional chloride-current assertion. The UniProt negative summary is considered alongside the mixed quenching/patch-clamp findings of PMID:20056604 and the negative PMID:21984732 assay. Retain the source-specific positive as secondary, without claiming universal native CaCC function. Unlike the cation experiments, chloride attribution is reported positively; minimally calcium-dependent liposome flux is not its gating evidence. Supporting Evidence: PMID:22946059 Ano4-10 are all able to produce transient Ca(2+)-activated Cl(-) currents PMID:20056604 Patch clamping of ANO-expressing FRT cells indicated that apart from ANO1 also ANO6 and 10 produced chloride currents, albeit with very different Ca(2+) sensitivity and activation time. PMID:39337485 ion currents attributed to the expression of ANO5, ANO9, or ANO10 were dependent on the presence (ANO9) or absence (ANO5 and -10) of ANO6 |
| GO:0005254 chloride channel activity | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: Broad chloride-channel activity has independent target support, with the rule chain unresolved. Reason: Exact ARBA rule conditions remain unreconstructed. Independent human PMID:22946059 channel/anion experiments support this conditional broad chloride-pore claim. Retain source-specific chain uncertainty without claiming exclusive or universal channel function. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: ARBA:ARBA00026476 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. Supporting Evidence: PMID:31477691 We found that TMEM16K functions as a non-selective channel in mixed chain length liposomes PMID:22946059 Ano4-10 are all able to produce transient Ca(2+)-activated Cl(-) currents PMID:39337485 ion currents attributed to the expression of ANO5, ANO9, or ANO10 were dependent on the presence (ANO9) or absence (ANO5 and -10) of ANO6 |
| GO:0005254 chloride channel activity | TAS Reactome:R-HSA-2684901 | KEEP AS NON CORE | Summary: The historical Reactome channel assignment represents a secondary ion-permeation capability. Reason: Historical Reactome family event fits conditional ANO10 channel results but adds no independent target experiment. Context-dependent ion permeation is secondary to directly demonstrated ER lipid scrambling. Supporting Evidence: PMID:31477691 We found that TMEM16K functions as a non-selective channel in mixed chain length liposomes PMID:22946059 Ano4-10 are all able to produce transient Ca(2+)-activated Cl(-) currents PMID:39337485 ion currents attributed to the expression of ANO5, ANO9, or ANO10 were dependent on the presence (ANO9) or absence (ANO5 and -10) of ANO6 |
| GO:0005886 plasma membrane | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Independent target observations support a surface pool, without resolving the exact ancestral node. Reason: Independent target evidence supports a secondary plasma-membrane pool: HPA016624 staining in human cells and the published PMID:22946059 extracellular-FLAG experiment in nonpermeabilized HEK293 cells expressing human ANO10. The latter is an overexpression result; its authors caution that native surface abundance may be low. Predominant ER residence and direct ER scramblase activity remain the core. The exact PTN000267334 IBD placement and inherited scope remain unresolved after local and official-source access checks. No loss or misplaced ancestral assertion has been demonstrated. Different node identifiers, donor counts and target self-inclusion do not establish propagation failure; the self-donor is legitimate descendant evidence. This retained location does not assert native plasma-membrane predominance or plasma-membrane scramblase activity. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: MGI:MGI:1918595 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. MGI:MGI:2142149 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. MGI:MGI:2143103 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. MGI:MGI:2145890 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. MGI:MGI:2387214 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. PANTHER:PTN000267334 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:A1A5B4 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:Q32M45 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:Q4KMQ2 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:Q5XXA6 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:Q6IWH7 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:Q75V66 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:Q9HCE9 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:Q9NQ90 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:Q9NW15 UNRESOLVED Target self-inclusion is legitimate descendant experimental grounding, not circularity. The exact ancestral node and its inherited scope remain unresolved. Supporting Evidence: file:human/ANO10/ANO10-notes.md The results show a spotted membrane expression of Ano10 file:human/ANO10/ANO10-notes.md Localized to the Plasma membrane (supported) |
| GO:0005886 plasma membrane | IDA GO_REF:0000052 | KEEP AS NON CORE | Summary: Target-specific HPA staining supports a secondary plasma-membrane pool. Reason: The actual HPA subcellular summary and assay table report supported plasma-membrane staining with HPA016624 in human BJ, HUVEC/TERT2 and U2OS cells. HUVEC/TERT2 is one cell line; individual image pixels were not independently scored. This positive target evidence supports a secondary pool. The distinct HPA051569 endogenous U2OS staining in PMID:31477691 supports the ER core and is not used as positive plasma-membrane evidence. Supporting Evidence: file:human/ANO10/ANO10-notes.md Localized to the Plasma membrane (supported) |
| GO:0005886 plasma membrane | IDA PMID:22946059 Anoctamins are a family of Ca2+-activated Cl- channels. | KEEP AS NON CORE | Summary: Human tagged ANO10 can reach the cell surface under the reported expression conditions. Reason: The original PMID:22946059 localization Results report extracellular-FLAG accessibility in nonpermeabilized HEK293 cells expressing human ANO10. Figure8 and the cDNA/immunocytochemistry Methods identify the human expression context. The authors describe weak surface staining and warn that native protein may not accumulate substantially at the plasma membrane. Retain the demonstrated expression-associated surface pool as non-core, without claiming native predominance; supplementary FigureS3 pixels were not independently inspected. The exact positive original-body passage is linked through the notes because the normal publication cache remains abstract-only. Supporting Evidence: file:human/ANO10/ANO10-notes.md The results show a spotted membrane expression of Ano10 |
| GO:0005886 plasma membrane | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: A surface pool is biologically supported, while the exact combined transfer remains unresolved. Reason: The exact combined mouse/Ensembl/subcellular transfer is not reconstructed. Independent human HPA observations and the published PMID:22946059 surface-labeling experiment corroborate the target location as a secondary pool. Neither that independent support nor predominant ER residence resolves the original donor experiment. No donor or ancestral placement is invented, and native plasma-membrane predominance is not asserted. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: UniProtKB:Q8BH79 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. ensembl:ENSMUSP00000045214 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB-SubCell:SL-0039 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. Supporting Evidence: file:human/ANO10/ANO10-notes.md The results show a spotted membrane expression of Ano10 file:human/ANO10/ANO10-notes.md Localized to the Plasma membrane (supported) |
| GO:0005886 plasma membrane | TAS Reactome:R-HSA-2684901 | KEEP AS NON CORE | Summary: The Reactome surface assignment is retained as a context-dependent location. Reason: Retain the historical Reactome surface location as a secondary context, independently corroborated by the published human ANO10 surface-labeling experiment. This reaction summary is not a new localization experiment. Weak overexpression-associated surface labeling does not establish predominant native residence; the direct ER scramblase mechanism remains the core. Supporting Evidence: file:human/ANO10/ANO10-notes.md The results show a spotted membrane expression of Ano10 |
| GO:0016020 membrane | HDA PMID:19946888 Defining the membrane proteome of NK cells. | MODIFY | Summary: Independent human localization refines the broad membrane annotation to ER membrane. Reason: The NK-cell membrane-proteome abstract does not expose the ANO10 peptide entry, so no source misattribution is alleged. Independent PMID:31477691 endogenous human U2OS staining and tagged-human ER-marker colocalization establish a more informative location. Refine to ER membrane without attributing that specificity to the original HDA survey. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: PMID:31477691 Together, these data are consistent with TMEM16K primarily residing in the ER membrane. |
| GO:0034220 monoatomic ion transmembrane transport | TAS Reactome:R-HSA-983712 | KEEP AS NON CORE | Summary: Ion transport is retained as a secondary capability supported independently of Reactome. Reason: Broad ion transport fits human PMID:22946059 currents and direct reconstituted PMID:31477691 flux. Secondary capability, with no causal edge from lipid scrambling to ion transport and no claim that Reactome adds a target experiment. Supporting Evidence: PMID:31477691 We found that TMEM16K functions as a non-selective channel in mixed chain length liposomes PMID:22946059 Ano4-10 are all able to produce transient Ca(2+)-activated Cl(-) currents |
| GO:0098655 monoatomic cation transmembrane transport | IEA GO_REF:0000108 | KEEP AS NON CORE | Summary: Broad cation transport is retained as an inference from purified-protein salt flux. Reason: Specific calcium-gated source MF remains uncertain, but broad cation movement is independently supported by purified-human nonselective KCl-gradient flux in PMID:31477691. No exclusive selectivity or native-surface inference. The endpoint measures retained chloride; cation movement is inferred from salt-gradient dissipation without ionophores, not measured as a potassium-selective current. The original GO:0005227 inference premise remains unresolved. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: GO:0005227 UNRESOLVED The narrow calcium-gated cation premise remains unresolved; retained broad transport instead has independent purified-protein salt-flux support. Supporting Evidence: PMID:31477691 determining whether a reconstituted protein dissipates a KCl gradient in the absence of ionophores |
| GO:1902476 chloride transmembrane transport | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Target experiments support secondary chloride transport without reconstructing the IBD node. Reason: Target PMID:22946059 is valid descendant evidence, not circular. Exact node placement is unavailable, but positive human anion experiments and purified nonselective flux support secondary chloride transport without claiming reconstructed PAINT reasoning. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: PANTHER:PTN002642655 UNRESOLVED The exact source chain or ancestral placement was not reconstructed. Independent target evidence and the annotation decision are assessed separately. UniProtKB:Q9NW15 UNRESOLVED Target self-inclusion is legitimate descendant experimental grounding, not circularity. The exact ancestral node and its inherited scope remain unresolved. Supporting Evidence: PMID:31477691 We found that TMEM16K functions as a non-selective channel in mixed chain length liposomes PMID:22946059 Ano4-10 are all able to produce transient Ca(2+)-activated Cl(-) currents |
| GO:1902476 chloride transmembrane transport | IDA PMID:22946059 Anoctamins are a family of Ca2+-activated Cl- channels. | KEEP AS NON CORE | Summary: Original human expression experiments support secondary chloride transport. Reason: Original human PMID:22946059 anion substitutions and currents support chloride transport in tested expression/stimulation settings. Retain secondary capability and distinguish context effects from absolute absence. Supporting Evidence: PMID:31477691 We found that TMEM16K functions as a non-selective channel in mixed chain length liposomes PMID:22946059 Ano4-10 are all able to produce transient Ca(2+)-activated Cl(-) currents |
| GO:0017128 phospholipid scramblase activity | IDA PMID:31477691 The structural basis of lipid scrambling and inactivation in... | NEW | Summary: Purified human ANO10 directly scrambles membrane phospholipids. Reason: PMID:31477691 studies full-length human TMEM16K expressed in insect or mammalian hosts and reconstituted into lipid vesicles. Dithionite-accessibility assays demonstrate transbilayer phospholipid movement, modulated by calcium and lipid composition, with residual activity without added calcium. This is direct biochemical activity distinct from the seeded channel terms. Plasma-membrane scrambling negatives in engineered cellular assays do not contradict an ER-like reconstituted lipid activity. Supporting Evidence: PMID:31477691 Thus, the slow rates of scrambling in 16:0–18:1 lipids reflect an intrinsic property of purified TMEM16K. PMID:39337485 our results do not exclude PL scrambling by ANO4, -8, or -10 in intracellular membranous compartments. |
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Download this section (compressed HTML)Q: How are ANO10 lipid scrambling and ion permeability coupled in native ER membranes, and which conditions explain its variable surface localization and cellular channel activity?
Q: Does ANO10 contribute a defined molecular step at ER–endosome contacts that directly explains its effects on endosomal sorting?
Q: Which expression backgrounds and current phases explain the reported effects of ANO10 on ANO1, and are they mediated directly or through calcium handling and membrane composition?
Experiment: Compare defined human ANO10 constructs with matched surface/ER abundance in ANO6-present and ANO6-null cells, measuring quenching and time-resolved currents at controlled calcium. Combine ANO1 coexpression with rescue and purified-protein reconstitution to separate direct permeation from effects on another channel.
Hypothesis: ANO10-associated cellular currents and ANO1 modulation depend on membrane targeting and other anoctamins.
Type: Controlled electrophysiology and reconstitution
Experiment: Compare wild-type and independently validated scrambling-deficient ANO10 at matched abundance and ER targeting, measuring lipid redistribution, split-GFP contact abundance and cargo sorting separately. Confirm the biochemical defect in purified protein before interpreting rescue failure.
Hypothesis: ER lipid scrambling contributes to sorting independently of mere contact-site proximity.
Type: Separation-of-function rescue
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