AAK1 is a cytosolic, peripheral-membrane serine/threonine kinase and endocytic scaffold of the Numb-associated kinase family. It is recruited through AP-2 and clathrin interactions and phosphorylates AP2M1/μ2 at Thr-156, increasing AP-2 affinity for cargo sorting motifs; assembled clathrin stimulates this activity. The long AAK1L isoform has an additional C-terminal clathrin-binding region and contributes to both cargo internalization and rapid recycling from early/sorting endosomes. Effects on uptake depend on cargo and cellular context and overlap with other NAK-family kinases. AAK1 also localizes to focal adhesions, where its kinase activity promotes adhesion disassembly and cell migration; PDLIM5 Thr-290 and talin-1 Thr-2270 are direct in-vitro AAK1/BMP2K substrates implicated in this output. More context-specific outputs include activated NOTCH1 stabilization and endosomal routing, WNT-LRP6 internalization, and TFR1-dependent iron uptake during ferroptosis.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0098793 presynapse | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: The IBA places AAK1 at the presynapse from a PANTHER family node and rat Aak1 evidence. This is biologically plausible, but it is a neuronal-context localization rather than the general core function of human AAK1. Reason: AAK1 was reported to be enriched at presynaptic terminals in cultured rat hippocampal neurons (PMID:11877461). Retain the phylogenetic localization as a conserved, context-specific site of action, without treating it as the universal location or defining function of human AAK1. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: PANTHER:PTN000539992 · PANTHER AAK1 family node SOURCE WEAK OR INFERRED The PANTHER node carries the phylogenetic inference and is not an independent localization experiment; it is correlated with the rat donor. RGD:1305520 · rat Aak1 SUPPORTS TRANSFER The rat ortholog is an appropriate donor for the conserved neuronal localization, although presynapse is contextual for the human protein. Supporting Evidence: PMID:11877461 In neuronal cells, AAK1 is enriched at presynaptic terminals |
| GO:0004674 protein serine/threonine kinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic assignment of protein serine/threonine kinase activity. This is the defining catalytic function of AAK1 and is independently established by direct biochemical studies. Reason: The IBA is at the appropriate specificity: human AAK1 is a catalytically active NAK-family serine/threonine kinase that phosphorylates AP2M1 and other protein substrates (PMID:11877457, PMID:11877461, PMID:42082516). Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000539992 · PANTHER AAK1 family node SOURCE WEAK OR INFERRED The family node is the inference carrier and is correlated with the rat donor rather than an independent biochemical observation. RGD:1305520 · rat Aak1 SUPPORTS TRANSFER The orthologous kinase supports transfer, and direct human biochemical evidence independently confirms the target function. Supporting Evidence: PMID:11877457 Together, these data suggest that AAK1 corresponds to the endogenous kinase responsible for phosphorylation of μ2 at Thr-156. |
| GO:0035612 AP-2 adaptor complex binding | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic assignment of binding to the AP-2 adaptor complex. Direct work shows AAK1 association with AP2 and interaction with the alpha-adaptin ear, making this a core substrate-recruitment/scaffolding function. Reason: AP-2 binding is directly tied to AAK1 recruitment and AP2M1 phosphorylation during clathrin-mediated endocytosis (PMID:11877461, PMID:12952931, PMID:17494869). The IBA lists the human target among its own sources, which is expected rather than self-supporting: AAK1's own IDA annotation to this term is one of the descendant evidences the PAINT curator used to place the IBD, so it marks that experimental grounding exists on the target itself. The IBA then adds the claim that the function is inherited rather than lineage-specific. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000539992 · PANTHER AAK1 family node SOURCE WEAK OR INFERRED This is the phylogenetic inference node, correlated with the donor set. RGD:1305520 · rat Aak1 SUPPORTS TRANSFER The rat ortholog supports conservation of AP-2 association. UniProtKB:Q2M2I8 · human AAK1 target record SUPPORTS TRANSFER Self-reference: the target is its own IBD seed, which is expected rather than circular -- its own IDA annotation to this term is one of the descendant evidences behind the IBD. The IBA then asserts the additional claim that the function is inherited rather than lineage-specific. Supporting Evidence: PMID:11877461 Thus, these results demonstrate that AAK1 interacts directly with α-adaptin in vitro. |
| GO:2000369 regulation of clathrin-dependent endocytosis | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic assignment of regulation of clathrin-dependent endocytosis. This is the central biological role of AAK1 and is supported by multiple direct perturbation and biochemical studies. Reason: AAK1 regulates cargo capture and coated-pit maturation through AP2M1 phosphorylation and has experimentally demonstrated effects on transferrin, LRP, and other cargo internalization (PMID:11877457, PMID:11877461, PMID:12952931, PMID:17494869, PMID:30605688, PMID:34315807). The PMID:12952931 uptake phenotype came from AAK1 overexpression, while about 80% knockdown produced no detectable uptake phenotype, so it is corroborating but not decisive evidence. The human target appears among the IBA sources and is treated as redundant rather than independent evidence. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000539992 · PANTHER AAK1 family node SOURCE WEAK OR INFERRED The family node is the correlated inference carrier. RGD:1305520 · rat Aak1 SUPPORTS TRANSFER Rat Aak1 supports conservation of the endocytic regulatory role. UniProtKB:F1SPM8 · pig AAK1 SUPPORTS TRANSFER Pig AAK1 is an orthologous donor supporting the transfer. UniProtKB:Q2M2I8 · human AAK1 target record SUPPORTS TRANSFER Self-reference: the target is its own IBD seed, which is expected rather than circular -- its own IDA/IMP annotation to this term is one of the descendant evidences behind the IBD. The IBA then asserts the additional claim that the function is inherited rather than lineage-specific. Supporting Evidence: PMID:11877461 Together, these results provide strong evidence that AAK1 is the endogenous mu 2 kinase and plays a regulatory role in clathrin-mediated endocytosis. |
| GO:0004672 protein kinase activity | IEA GO_REF:0000002 | MODIFY | Summary: InterPro electronically maps the AAK1 kinase-domain signature to the broad term protein kinase activity. The catalytic class is correct, but a more informative serine/threonine-specific term is already supported directly. Reason: AAK1 is not merely an unspecified protein kinase; biochemical and structural evidence establishes serine/threonine protein kinase activity. Replace the broad parent with GO:0004674, consolidating with existing GO:0004674 rows. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: InterPro:IPR008271 · protein kinase active-site signature SUPPORTS SOURCE BUT NOT TARGET The signature supports kinase activity but the electronic mapping is broader than the experimentally established serine/threonine specificity; it is also correlated with the other kinase-domain mappings. Proposed replacements: protein serine/threonine kinase activity Supporting Evidence: PMID:11877461 Here we identify and characterize a novel member of the Prk/Ark family of serine/threonine kinases, adaptor-associated kinase (AAK)1. |
| GO:0004674 protein serine/threonine kinase activity | IEA GO_REF:0000003 | ACCEPT | Summary: EC-to-GO electronic assignment of protein serine/threonine kinase activity. It matches AAK1's experimentally established catalytic class. Reason: EC 2.7.11.1 is correctly mapped to the core molecular function, which is independently supported by direct AP2M1 phosphorylation and human AAK1 kinase structures. The EC mapping is corroborative and correlated with the other electronic kinase-domain rows, not a separate experiment. Propagation Review Root cause: NO FAILURE CORE Sources checked: EC:2.7.11.1 · non-specific serine/threonine protein kinase EC class SUPPORTS TRANSFER The EC mapping has the correct catalytic scope; it is an electronic classification correlated with the InterPro and Rhea mappings. |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro kinase-domain mapping to ATP binding. ATP binding is mechanistically correct for AAK1 but is generic relative to its informative catalytic activity. Reason: The AAK1 kinase domain contains the conserved ATP-binding pocket and direct structural work resolves inhibitor binding in that pocket (PMID:26853940). Retain the annotation as a valid cofactor-binding property, but do not elevate generic ATP binding to a core functional summary. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: InterPro:IPR000719 · protein kinase domain SUPPORTS TRANSFER The domain supports ATP binding, but this electronic row is correlated with the other kinase-domain mappings and adds no independent experiment. Supporting Evidence: PMID:26853940 Here we report the first high-resolution structures of kinases AAK1 and BIKE in complex with two drug candidates. |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Electronic localization to the plasma membrane derived from the UniProt subcellular-location vocabulary. This is consistent with AAK1 action at plasma-membrane clathrin-coated pits and with direct human-cell imaging. Reason: AAK1 acts peripherally at the plasma membrane during cargo internalization. Direct RPE-cell imaging found broad plasma-membrane AAK1 distribution (PMID:42082516), independently supporting the location. The vocabulary mapping is generated from the same UniProt target record and is therefore correlated, not an independent localization experiment. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB-SubCell:SL-0039 · UniProt cell membrane vocabulary term CIRCULAR OR REDUNDANT This IEA maps the target record's own subcellular-location statement; it is valid but self-derived and correlated with other UniProt location rows. Supporting Evidence: PMID:42082516 In contrast, AAK1 is broadly distributed across the PM, with 40% lower fluorescence intensity in CCPs in comparison to BMP2K. |
| GO:0005905 clathrin-coated pit | IEA GO_REF:0000044 | ACCEPT | Summary: Electronic localization to clathrin-coated pits from the UniProt subcellular-location vocabulary. This is a principal site at which AAK1 controls AP2 and cargo capture. Reason: Direct localization and biochemical work place AAK1 with AP2 and clathrin at coated pits (PMID:11877461), while clathrin activates AAK1 (PMID:14617351). The mapping is correct but derives from the same UniProt record, so it should not be counted as independent evidence. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB-SubCell:SL-0069 · UniProt clathrin-coated pit vocabulary term CIRCULAR OR REDUNDANT This is a self-derived vocabulary mapping from the AAK1 UniProt record, correlated with its other mapped localization rows. Supporting Evidence: PMID:11877461 AAK1 also colocalized to endocytic structures in nonneuronal cells. |
| GO:0098793 presynapse | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Electronic presynapse localization mapped from the UniProt record. The location is plausible from neuronal ortholog evidence but is tissue-specific. Reason: Rat-neuron experiments reported enrichment at presynaptic terminals (PMID:11877461). Retain this as contextual neuronal localization rather than a general core location of human AAK1. Because the IEA is mapped from the target record's own location statement, it is correlated/self-derived. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: UniProtKB-SubCell:SL-0516 · UniProt presynapse vocabulary term CIRCULAR OR REDUNDANT The source is the target record's own vocabulary assertion and is not an independent human presynaptic localization experiment. Supporting Evidence: PMID:11877461 In neuronal cells, AAK1 is enriched at presynaptic terminals |
| GO:0106310 protein serine kinase activity | IEA GO_REF:0000116 | ACCEPT | Summary: Rhea electronically maps the serine-specific protein phosphorylation reaction to the current protein serine kinase activity term. This is one valid subactivity within AAK1's broader serine/threonine kinase activity. Reason: RHEA:17989 directly supports the serine-specific electronic mapping, and this annotation can coexist with the broader GO:0004674 rows. AAK1 also has strong threonine-substrate evidence, but current GO has no separate primary protein threonine kinase term: GO:0106311 is an alternate ID of GO:0004674, not a usable sibling term. Retain the valid serine subactivity rather than generalizing it or writing an alternate identifier. Propagation Review Root cause: NO FAILURE CORE Sources checked: RHEA:17989 · L-seryl-protein phosphorylation reaction SUPPORTS TRANSFER The reaction directly supports the serine subactivity. It is correlated with the UniProt catalytic record and does not negate AAK1's independently supported threonine activity. |
| GO:0005515 protein binding | IPI PMID:22645275 Identification of novel ATP13A2 interactors and their role i... | MARK AS OVER ANNOTATED | Summary: GOA/IntAct records AAK1 as an ATP13A2 interactor from a yeast two-hybrid screen. The cached abstract describes the 43-interactor screen but does not name AAK1, and the full text is unavailable locally, so the specific pair cannot be independently verified here. Reason: Retain and defer to the experimental interaction provenance; this action does not reject or question the AAK1-ATP13A2 pair. It concerns only GO:0005515, which is an uninformative generic molecular-function term and does not capture the interaction partner, mechanism, or biological role. Mark the term as over-annotated while recording that the pair-level evidence remains unverified from the locally accessible abstract. Supporting Evidence: PMID:22645275 Utilizing a split-ubiquitin membrane yeast two-hybrid system that was developed to identify interacting partners of full-length integral membrane proteins, we identified 43 novel interactors |
| GO:0061024 membrane organization | TAS Reactome:R-HSA-199991 | KEEP AS NON CORE | Summary: Reactome assigns AAK1 to the broad membrane-trafficking umbrella and maps that participation to membrane organization. This captures pathway context but is broader than AAK1's specific clathrin-mediated endocytic role. Reason: Membrane organization is defensible as a high-level consequence of AAK1's endocytic function, but the core role is regulation of clathrin-dependent endocytosis through AP2M1 phosphorylation. Retain this TAS annotation as broad pathway context rather than as a defining function. |
| GO:0004674 protein serine/threonine kinase activity | TAS Reactome:R-HSA-8856813 | ACCEPT | Summary: Reactome represents AAK1 phosphorylating the AP-2 mu subunit and maps the event to protein serine/threonine kinase activity. This matches the core catalytic function established experimentally. Reason: The pathway event is consistent with direct biochemical evidence that AAK1 phosphorylates AP2M1 at Thr-156 (PMID:11877457). Although the TAS is model based, its catalytic assertion is correctly scoped and independently supported. Supporting Evidence: PMID:11877457 Together, these data suggest that AAK1 corresponds to the endogenous kinase responsible for phosphorylation of μ2 at Thr-156. |
| GO:0005886 plasma membrane | IDA GO_REF:0000052 | ACCEPT | Summary: Human Protein Atlas immunofluorescence places AAK1 at the plasma membrane. This agrees with its role at plasma-membrane clathrin-coated pits. Reason: The direct human-cell localization is biologically consistent with AAK1 cargo internalization and with independent live-cell evidence of plasma-membrane distribution (PMID:42082516). Retain the experimentally assigned location. Supporting Evidence: PMID:42082516 In contrast, AAK1 is broadly distributed across the PM, with 40% lower fluorescence intensity in CCPs in comparison to BMP2K. |
| GO:0005886 plasma membrane | ISS GO_REF:0000024 | ACCEPT | Summary: Plasma-membrane localization transferred by curator-reviewed similarity from bovine AAK1. This is conserved and independently supported in human cells. Reason: The bovine ortholog is an appropriate donor and direct imaging of human AAK1 supports plasma-membrane distribution (PMID:42082516). The same donor is reused for multiple location rows, so those ISS annotations are correlated rather than independent observations. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB:F1MH24 · bovine AAK1 SUPPORTS TRANSFER The ortholog supports transfer; reuse of this single donor for plasma membrane and coated pit makes the inferred rows correlated. Supporting Evidence: PMID:42082516 In contrast, AAK1 is broadly distributed across the PM, with 40% lower fluorescence intensity in CCPs in comparison to BMP2K. |
| GO:0098793 presynapse | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Presynapse localization transferred from rat Aak1. The inference is plausible and supported in rat neurons, but it is a neuronal-context location. Reason: Preserve the ortholog transfer because rat-neuron experiments place AAK1 at presynaptic terminals (PMID:11877461), while recognizing that the human row is model-derived and should not define AAK1's general cellular location. This and other P0C1X8 transfers reuse one donor and are correlated. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: UniProtKB:P0C1X8 · rat Aak1 SUPPORTS TRANSFER Rat Aak1 supports the neuronal localization; reuse of this donor across kinase and neuronal-location rows does not constitute independent evidence. Supporting Evidence: PMID:11877461 In neuronal cells, AAK1 is enriched at presynaptic terminals |
| GO:0005905 clathrin-coated pit | ISS GO_REF:0000024 | ACCEPT | Summary: Clathrin-coated-pit localization transferred from bovine AAK1. The location is central to AAK1's endocytic role and is independently observed in human cells. Reason: AAK1 colocalizes with AP2 and clathrin at coated-pit structures and is activated by assembled clathrin (PMID:11877461, PMID:14617351). The bovine donor is sound, but its reuse with the plasma-membrane ISS row makes the evidence correlated. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB:F1MH24 · bovine AAK1 SUPPORTS TRANSFER Bovine AAK1 is a suitable orthologous donor; this is the same donor used for the plasma-membrane transfer and is not an independent second source. Supporting Evidence: PMID:11877461 AAK1 also colocalized to endocytic structures in nonneuronal cells. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8856808 | KEEP AS NON CORE | Summary: The Reactome AP-2/clathrin recruitment event models AAK1 as cytosolic before or during recruitment to the endocytic machinery. Reason: A cytosolic pool is plausible for this peripheral-membrane kinase, but this TAS is generated from a shared Reactome clathrin-mediated-endocytosis model. The 17 Reactome cytosol rows are correlated pathway-context assertions, not independent localization experiments; retain each as non-core context. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8856813 | KEEP AS NON CORE | Summary: The Reactome AP2M1 phosphorylation event assigns its AAK1 participant to the cytosol. Reason: Cytosolic availability is compatible with recruitment of AAK1 to coated pits, but the location is model context rather than a direct assay. It is correlated with the other 16 cytosol tuples emitted from the same Reactome pathway and is retained as non-core. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8866283 | KEEP AS NON CORE | Summary: Reactome assigns cytosolic AAK1 in the modeled recruitment of GPCRs to clathrin-coated pits. Reason: This is a correlated participant-location assertion from the shared Reactome endocytosis model, not an independent localization experiment or a distinct AAK1 function. Retain it as non-core pathway context. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8867754 | KEEP AS NON CORE | Summary: Reactome places AAK1 in the cytosol in the modeled F-/N-BAR protein recruitment phase of coated-pit maturation. Reason: The cytosolic location is biologically compatible with a recruitable peripheral kinase, but this tuple is one of 17 correlated annotations generated from the same pathway model. Keep it as non-core context rather than independent support. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8867756 | KEEP AS NON CORE | Summary: Reactome assigns cytosolic AAK1 in a modeled nascent coated-pit cargo/CLASP recruitment event. Reason: This pathway-derived location is plausible but does not establish a separate localization result. It is correlated with the other Reactome cytosol rows and is retained as non-core endocytic context. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868071 | KEEP AS NON CORE | Summary: Reactome places AAK1 in the cytosol in the clathrin-dependent PIK3C2A recruitment event. Reason: The TAS reflects a shared pathway compartment rather than an AAK1-specific localization experiment. It is correlated with the 16 other Reactome cytosol rows and is retained only as non-core pathway context. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868072 | KEEP AS NON CORE | Summary: Reactome assigns cytosolic AAK1 in the modeled PIK3C2A phosphoinositide phosphorylation stage of coated-pit maturation. Reason: This is a pathway-participant compartment assignment, not direct evidence that independently localizes AAK1. Treat it as correlated with the other Reactome cytosol tuples and retain it as non-core context. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868230 | KEEP AS NON CORE | Summary: Reactome assigns cytosolic AAK1 in the modeled SNX9/actin-machinery recruitment stage of clathrin-mediated endocytosis. Reason: The location derives from the common pathway model and is not an independent AAK1 localization assay. It is correlated with the other 16 cytosol rows and should remain non-core. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868236 | KEEP AS NON CORE | Summary: Reactome places AAK1 in the cytosol in a modeled BAR-protein/dynamin recruitment event. Reason: Cytosol is plausible for the unbound pool, but this TAS is a correlated pathway-context assertion rather than direct localization evidence. Retain it as non-core. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868648 | KEEP AS NON CORE | Summary: Reactome assigns cytosolic AAK1 in the modeled synaptojanin lipid-hydrolysis stage of coated-vesicle formation. Reason: This tuple inherits the pathway compartment and is not independent evidence for AAK1 localization or synaptojanin regulation. It is correlated with the other Reactome cytosol rows and is retained as non-core context. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868651 | KEEP AS NON CORE | Summary: Reactome places AAK1 in the cytosol in the modeled endophilin/synaptojanin recruitment event. Reason: The assignment is a shared pathway-location statement, not an AAK1-specific experiment. It is correlated with the other 16 Reactome cytosol annotations and is kept only as non-core context. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868658 | KEEP AS NON CORE | Summary: Reactome assigns cytosolic AAK1 in the modeled HSPA8-driven vesicle-uncoating event. Reason: This is correlated compartment context from a broader endocytosis model, not evidence that AAK1 directly performs or controls HSPA8 ATP hydrolysis. Retain the cytosol tuple as non-core. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868659 | KEEP AS NON CORE | Summary: Reactome places AAK1 in the cytosol in the modeled recruitment of auxilins to clathrin-coated vesicles. Reason: The TAS derives from the shared pathway compartment rather than a direct AAK1 localization assay. It is correlated with the other Reactome cytosol tuples and is retained as non-core context. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868660 | KEEP AS NON CORE | Summary: Reactome assigns cytosolic AAK1 in the modeled auxilin/HSPA8 recruitment event. Reason: This participant-location row is correlated with the common Reactome pathway model and does not provide an independent localization observation. Retain it as non-core context. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868661 | KEEP AS NON CORE | Summary: Reactome places AAK1 in the cytosol in the modeled dynamin-mediated vesicle scission event. Reason: The tuple inherits a pathway compartment and should not be interpreted as separate evidence that AAK1 controls dynamin catalysis. It is correlated with the other 16 cytosol annotations and is retained as non-core context. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8871193 | KEEP AS NON CORE | Summary: Reactome assigns cytosolic AAK1 in the modeled dissociation of AAK1 and dephosphorylation of AP2M1. Reason: Cytosolic release after coated-pit action is mechanistically plausible, but this is model-derived and correlated with the other Reactome cytosol rows. It is retained as non-core rather than treated as direct localization evidence. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8871194 | KEEP AS NON CORE | Summary: Reactome places AAK1 in the cytosol in the modeled RAB5/GAPVD1 binding phase of the AP-2 endocytic pathway. Reason: The TAS is a correlated pathway-participant compartment assignment, not a distinct AAK1 localization experiment. Retain it as non-core context with the other Reactome cytosol tuples. |
| GO:0004674 protein serine/threonine kinase activity | ISS GO_REF:0000024 | ACCEPT | Summary: Protein serine/threonine kinase activity transferred from rat Aak1 by curator-reviewed similarity. This is the defining catalytic activity and is independently established for human AAK1. Reason: The rat ortholog is an appropriate donor, and direct biochemical and structural studies of human AAK1 confirm an active serine/threonine kinase (PMID:11877457, PMID:11877461, PMID:26853940). The same donor is reused for several localization rows, so those transfers are correlated rather than independent support. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB:P0C1X8 · rat Aak1 SUPPORTS TRANSFER Rat Aak1 is a suitable orthologous donor; reuse of this one donor across kinase, presynapse, leading-edge, and bouton rows is correlated evidence. Supporting Evidence: PMID:11877457 Together, these data suggest that AAK1 corresponds to the endogenous kinase responsible for phosphorylation of μ2 at Thr-156. |
| GO:0005112 Notch binding | IDA PMID:21464124 The adaptor-associated kinase 1, AAK1, is a positive regulat... | KEEP AS NON CORE | Summary: AAK1 directly binds the membrane-tethered activated form of NOTCH1, but not the inactive full-length receptor, in a ligand-activation/endocytic context. Reason: The IDA is directly supported and more informative than generic protein binding. Retain it as a context-specific interaction that helps route activated NOTCH1, rather than treating Notch binding as the defining molecular function of AAK1. Supporting Evidence: PMID:21464124 We show here that AAK1, the adaptor-associated kinase 1, directly interacts with the membrane-tethered active form of Notch released by metalloprotease cleavage. |
| GO:0006468 protein phosphorylation | IDA PMID:17494869 A novel AAK1 splice variant functions at multiple steps of t... | MODIFY | Summary: AAK1L and AAK1S were tested in kinase assays against the AP-2 mu2 subunit, whose established AAK1 phosphosite is Thr-156. Reason: The study directly assayed both human splice forms and found basal and clathrin-stimulated AP2M1 kinase activity. Replace the broad process term with GO:0018107 peptidyl-threonine phosphorylation, supported by direct mapping of the AAK1-dependent AP2M1 site to Thr-156 in PMID:11877457. Proposed replacements: peptidyl-threonine phosphorylation Supporting Evidence: PMID:17494869 However, in vitro kinase assays reveal little difference between AAK1 isoforms in their basal or clathrin-stimulated kinase activity toward the AP-2 micro2 subunit. PMID:11877457 Phosphorylation of mu 2 occurs at a single threonine residue (Thr-156) and is mediated by the newly discovered adaptor-associated kinase, AAK1, which copurifies with AP2. |
| GO:0006468 protein phosphorylation | IDA PMID:18657069 AAK1 regulates Numb function at an early step in clathrin-me... | MODIFY | Summary: The source reports AAK1-dependent phosphorylation of NUMB and identifies T102 as the relevant site. A 2026 biochemical study did not detect phosphorylation of a NUMB T102 peptide, creating substrate-site-specific counterevidence. Reason: Replace the broad process term with GO:0018107 peptidyl-threonine phosphorylation. The original study reports a threonine phosphosite, while AP2M1 T156 and newer PDLIM5/Talin1 sites independently establish AAK1-mediated threonine phosphorylation. This replacement does not endorse NUMB T102 as a physiological substrate: that specific assignment is disputed by PMID:42082516. Proposed replacements: peptidyl-threonine phosphorylation Supporting Evidence: PMID:18657069 In this study, we show that Numb binds to and is phosphorylated by adaptor-associated kinase 1 (AAK1), a key endocytic kinase. PMID:42082516 This refined consensus sequence also explains why previously proposed substrates Dab2 T109, Arh T104, NUMB T102, and AP1μ T14426 showed no detectable phosphorylation in our in-vitro experiments |
| GO:0030136 clathrin-coated vesicle | ISS GO_REF:0000024 | ACCEPT | Summary: Clathrin-coated-vesicle localization transferred from pig AAK1. This is consistent with AAK1 association with AP2, clathrin, and isolated coated vesicles during its core endocytic function. Reason: The pig ortholog is an appropriate donor, and biochemical fractionation of mammalian tissues independently recovered AAK1 with clathrin-coated vesicles (PMID:11877461). This donor also supports an IBA process row, making those propagated assertions correlated rather than independent. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB:F1SPM8 · pig AAK1 SUPPORTS TRANSFER Pig AAK1 supports the conserved coated-vesicle location; reuse of this donor in the IBA endocytosis row is correlated evidence. Supporting Evidence: PMID:11877461 AAK1 is found associated with isolated APs (lane 1), clathrin (lane 2), and CCVs (lane 3), and CCVs from rat liver (lane 4). |
| GO:0031252 cell leading edge | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Cell-leading-edge localization transferred from rat Aak1. Direct human-cell work supports leading-edge/endocytic and focal-adhesion recruitment during migration, but this is context-dependent. Reason: Human HeLa imaging reported AAK1 enrichment at the leading edge (PMID:11877461), and newer RPE-cell work links AAK1 recruitment to focal adhesion turnover and migration (PMID:42082516). Retain this localization as a non-core migratory-cell context. The rat donor is reused across several ISS rows and thus does not create independent evidence for each. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: UniProtKB:P0C1X8 · rat Aak1 SUPPORTS TRANSFER Rat Aak1 is an appropriate donor, but this single donor is shared with the kinase, presynapse, and terminal-bouton ISS rows. Supporting Evidence: PMID:11877461 Interestingly, in migrating cells AAK1 was highly enriched at the leading edge |
| GO:0032880 regulation of protein localization | IDA PMID:18657069 AAK1 regulates Numb function at an early step in clathrin-me... | KEEP AS NON CORE | Summary: AAK1 perturbation changes NUMB distribution between the plasma membrane and perinuclear endosomes, directly supporting regulation of protein localization. Reason: Preserve the reported localization phenotype even though the proposed direct phosphorylation of NUMB T102 is challenged by PMID:42082516. The redistribution result supports a real, substrate/context-specific regulatory output, but it is secondary to AAK1's core AP2/endocytic function. Supporting Evidence: PMID:18657069 We find that AAK1 redistributes Numb to perinuclear endosomes when overexpressed, while kinase depletion causes Numb to accumulate at the plasma membrane. PMID:42082516 This refined consensus sequence also explains why previously proposed substrates Dab2 T109, Arh T104, NUMB T102, and AP1μ T14426 showed no detectable phosphorylation in our in-vitro experiments |
| GO:0035612 AP-2 adaptor complex binding | IDA PMID:17494869 A novel AAK1 splice variant functions at multiple steps of t... | ACCEPT | Summary: The source supports association of AAK1 isoforms with the AP-2 machinery and assays AP2M1 as their kinase substrate. Reason: Although the locally cached source exposes only the abstract and does not spell out every binding assay, the experimental curator had access to the full study. Direct AP-2/alpha-adaptin binding was independently demonstrated in PMID:11877461, so the informative AP-2-complex-binding term is retained. Supporting Evidence: PMID:11877461 Thus, these results demonstrate that AAK1 interacts directly with α-adaptin in vitro. |
| GO:0043195 terminal bouton | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Terminal-bouton localization transferred from rat Aak1. It is compatible with reported presynaptic-terminal enrichment but is a neuronal model-derived sublocation rather than a general human AAK1 location. Reason: Keep the ortholog transfer as contextual neuronal localization. The cached experimental evidence supports presynaptic-terminal enrichment (PMID:11877461) but not a uniquely required terminal-bouton role, and the same rat donor is reused across multiple ISS rows. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: UniProtKB:P0C1X8 · rat Aak1 SUPPORTS TRANSFER The donor supports neuronal terminal localization, but this is the same source reused for presynapse, kinase, and leading-edge transfers. Supporting Evidence: PMID:11877461 In neuronal cells, AAK1 is enriched at presynaptic terminals |
| GO:0045747 positive regulation of Notch signaling pathway | IDA PMID:21464124 The adaptor-associated kinase 1, AAK1, is a positive regulat... | KEEP AS NON CORE | Summary: AAK1 promotes activated NOTCH1 routing and transcriptional output upstream of gamma-secretase, supporting positive regulation of Notch signaling in the tested ligand-activation context. Reason: The direct perturbation evidence supports a positive effect on mammalian Notch signaling. Retain it as a context-specific signaling consequence of AAK1's endocytic/adaptor activity, rather than as the kinase's universal core process. Supporting Evidence: PMID:21464124 Moreover, shRNA-mediated AAK1 depletion decreases Notch transcriptional activity in coculture experiments. |
| GO:0050821 protein stabilization | IDA PMID:21464124 The adaptor-associated kinase 1, AAK1, is a positive regulat... | KEEP AS NON CORE | Summary: AAK1 stabilizes the membrane-tethered activated NOTCH1 fragment and its monoubiquitinated counterpart upstream of gamma-secretase cleavage. Reason: The IDA is supported for the specific activated-NOTCH1 experimental context. Protein stabilization is a secondary, substrate-specific output of AAK1 adaptor/endocytic activity and should not be treated as its defining process. Supporting Evidence: PMID:21464124 Active AAK1 acts upstream of the γ-secretase cleavage by stabilizing both the membrane-tethered activated form of Notch and its monoubiquitinated counterpart. |
| GO:2000369 regulation of clathrin-dependent endocytosis | IMP PMID:17494869 A novel AAK1 splice variant functions at multiple steps of t... | ACCEPT | Summary: AAK1L-domain overexpression and AAK1 depletion perturb transferrin internalization and recycling, directly demonstrating regulation at multiple steps of the clathrin-dependent endocytic pathway. Reason: This IMP annotation captures the central biological role established by perturbation of AAK1 constructs and abundance. Cargo and direction of effect vary with experimental context, so the sign-neutral regulatory GO term is appropriately scoped. Supporting Evidence: PMID:17494869 These observations suggest that AAK1 functions at multiple steps of the endosomal pathway by regulating transferrin internalization and its rapid recycling back to the plasma membrane from early/sorting endosome. |
| GO:2000369 regulation of clathrin-dependent endocytosis | IDA PMID:18657069 AAK1 regulates Numb function at an early step in clathrin-me... | ACCEPT | Summary: AAK1 perturbation and NUMB localization/mutant experiments support regulation of cargo-selective clathrin-dependent endocytosis and coated-pit maturation. Reason: Preserve the broad endocytic-regulation annotation: the reported NUMB redistribution and transferrin/LDL uptake phenotypes support it, and AAK1's endocytic role is independently established (PMID:11877461, PMID:17494869). PMID:42082516 disputes direct phosphorylation of the proposed NUMB T102 peptide, so that specific mechanism is treated cautiously without discarding the phenotype or the broader process. Supporting Evidence: PMID:18657069 Overexpression of a Numb point mutant (T102A) that lacks the AAK1 phosphorylation site potently disrupts transferrin and low-density lipoprotein internalization but does not impact EGF uptake. PMID:42082516 This refined consensus sequence also explains why previously proposed substrates Dab2 T109, Arh T104, NUMB T102, and AP1μ T14426 showed no detectable phosphorylation in our in-vitro experiments |
| GO:0030276 clathrin binding | IDA Q2M2I8-1 PMID:17494869 A novel AAK1 splice variant functions at multiple steps of t... | NEW | Summary: NEW annotation. The long AAK1 isoform contains a second C-terminal clathrin-binding region whose direct interaction with clathrin was tested in protein-interaction assays. Reason: Clathrin binding is an informative molecular function that helps recruit and stimulate AAK1 in the coated-pit machinery. The isoform field records that the tested CBD2 construct came from long isoform AAK1L/Q2M2I8-1; it does not claim that clathrin binding is unique to this isoform. Supporting Evidence: PMID:17494869 Protein interaction studies demonstrate that AAK1L CBD2 directly binds clathrin. |
| GO:2001137 positive regulation of endocytic recycling | IMP Q2M2I8-1 PMID:17494869 A novel AAK1 splice variant functions at multiple steps of t... | NEW | Summary: NEW annotation. AAK1 depletion or interference with its second clathrin-binding region impairs transferrin recycling from early/sorting endosomes, and independent depletion experiments delay short-loop beta3 integrin recycling to the cell surface. Reason: Loss-of-function evidence for two cargos supports a positive contribution to endocytic recycling, a process not captured by the existing annotation to regulation of clathrin-dependent endocytosis. The isoform field records the tested long AAK1L/Q2M2I8-1 constructs without claiming that the shorter isoform cannot contribute. Supporting Evidence: PMID:17494869 Surprisingly, CBD2 overexpression or AAK1 depletion by RNA interference significantly impairs transferrin recycling from the early/sorting endosome. PMID:23781025 siRNA-mediated depletion of either factor delays short-loop β3 integrin recycling from the early endosome back to the cell surface. |
| GO:0005925 focal adhesion | IDA PMID:42082516 AAK1-mediated phosphorylation of PDLIM5 and Talin1 promotes ... | NEW | Summary: NEW annotation. Live-cell imaging places AAK1 at mature, tension-bearing focal adhesions in collagen-adherent human RPE cells. Reason: The ECM-dependent localization was supported by paxillin colocalization and multiple illumination, membrane, and attachment controls. This is the site of AAK1's directly demonstrated adhesion-turnover activity. Supporting Evidence: PMID:42082516 Thus, AAK1 is specifically recruited to mature, tension-bearing FAs and thereby positioned to efficiently phosphorylate substrates PDLIM5 and Talin1. |
| GO:0120183 positive regulation of focal adhesion disassembly | IMP PMID:42082516 AAK1-mediated phosphorylation of PDLIM5 and Talin1 promotes ... | NEW | Summary: NEW annotation. AAK1 deletion increases focal-adhesion density and lifetime and slows paxillin exchange, while kinase- and phosphosite-dependent analyses support accelerated release of focal-adhesion components. Reason: Human-cell loss-of-function, live imaging, rescue, and phosphomutant evidence directly supports a positive regulatory role in focal-adhesion disassembly. This is a core AAK1 function distinct from its cargo-trafficking role. Supporting Evidence: PMID:42082516 Because rapid paxillin turnover is essential for efficient cell migration, these data position AAK1 as a positive regulator of FA disassembly and motility. |
| GO:0030335 positive regulation of cell migration | IMP PMID:42082516 AAK1-mediated phosphorylation of PDLIM5 and Talin1 promotes ... | NEW | Summary: NEW annotation. AAK1 knockout or knockdown slows human RPE-cell migration, with corroborating knockdown phenotypes in SH-SY5Y and MDA-MB-231 cells. Reason: Genetic loss and kinase-inhibitor phenotypes establish a positive, kinase-dependent contribution to cell migration. BMP2K loss did not reproduce the RPE phenotype, supporting an AAK1-specific core role. Supporting Evidence: PMID:42082516 AAK1 deletion or siRNA-mediated knockdown reproducibly impaired RPE migration by ~25% (Fig. 3d, e and Supplementary Fig. 1h), whereas BMP2K loss had no measurable effect, revealing a specific and non-redundant role for AAK1 in cell motility. |
| GO:0090090 negative regulation of canonical Wnt signaling pathway | IMP PMID:30605688 WNT Activates the AAK1 Kinase to Promote Clathrin-Mediated E... | NEW | Summary: NEW annotation. AAK1 loss or inhibition increases canonical WNT output in multiple human cell models, while AAK1 promotes LRP6 endocytosis and lysosomal degradation. Reason: Perturbation and mechanistic evidence support negative regulation of canonical WNT signaling. This is retained as a context- and cargo-specific output of the endocytic machinery, not as a universal core function of AAK1. Supporting Evidence: PMID:30605688 Together, these results suggest that AAK1 inhibits WNT signaling by inducing CME endocytosis and lysosomal degradation of LRP6. |
| GO:0160020 positive regulation of ferroptosis | IMP PMID:41407700 AAK1 activation-mediated iron trafficking drives ferroptotic... | NEW | Summary: NEW annotation. In induced ferroptosis models, AAK1 loss reduces lipid peroxidation and ferroptotic death, whereas activated AAK1 drives AP2M1-dependent TFR1 internalization and iron accumulation. Reason: Genetic and mechanistic evidence supports positive regulation of ferroptosis in the tested cancer-cell and xenograft settings. This stimulus-dependent, cargo-specific role is non-core rather than a constitutive output of AAK1. Supporting Evidence: PMID:41407700 Mechanistically, activated AAK1 phosphorylates AP2M1, which facilitates the recruitment of clathrin to mediate the endocytosis of TFR1, increasing the levels of both cellular total iron and ferrous iron and thereby promoting ferroptosis. |
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Download this section (compressed HTML)Q: Which cargo classes and human cell types depend nonredundantly on AAK1, rather than BMP2K, GAK, or another kinase, for AP2M1 phosphorylation, internalization, and endocytic recycling?
Q: Do AAK1L and AAK1S differ in recruitment to coated pits, early endosomes, and focal adhesions, or in their relative contributions to recycling and adhesion turnover?
Experiment: Generate matched endogenous AAK1, BMP2K, GAK, and combinatorial acute-degron cell panels in several human lineages. Measure AP2M1 Thr-156 phosphorylation, coated-pit dynamics, and uptake/recycling kinetics for transferrin receptor, integrins, LRP6, and TFR1, with wild-type and kinase-dead rescues.
Hypothesis: AAK1 and BMP2K make cell- and cargo-specific, partly compensatory contributions to AP2M1 phosphorylation and endocytic flux.
Type: Acute genetic perturbation, targeted phosphoproteomics, and quantitative live-cell endocytic trafficking
Experiment: Use isoform-selective CRISPR editing and endogenous fluorescent tagging to compare AAK1L and AAK1S recruitment at coated pits, early endosomes, and focal adhesions. Combine isoform-specific rescue with AP2M1, PDLIM5, and talin-1 phosphosite measurements, cargo recycling, focal-adhesion lifetime, and migration assays.
Hypothesis: AAK1 isoforms and C-terminal recruitment motifs partition its endocytic and focal-adhesion activities.
Type: Isoform-resolved genome editing, live-cell imaging, and targeted phosphoproteomics
What is not known — curated, literature-grounded statements of the open unknowns (the inverse of core functions).
Gap: The cargo- and cell-type-specific division of AP2M1 phosphorylation and clathrin-dependent endocytosis among AAK1, BMP2K, GAK, and other kinases is not resolved.
NARROWING BIOLOGY RESIDUAL_SUBGAP
What is known: AAK1 directly phosphorylates AP2M1 and regulates endocytosis and recycling in multiple systems, but in human RPE cells BMP2K is the dominant NAK for receptor internalization while AAK1 loss has only a modest effect on AP2M1 phosphorylation.
Significance: Resolving the division of labor is necessary to predict which cargos and tissues will respond to selective AAK1 perturbation and to avoid treating all NAK-family endocytic evidence as interchangeable.
What would resolve it: Parallel endogenous single- and combinatorial-kinase perturbations, coupled to AP2M1 phosphosite quantification and cargo-resolved uptake and recycling assays across cell types, would define nonredundant and compensatory roles.
Provenance (the field's own admissions):
Gap: The individual contribution of AAK1 versus BMP2K to endogenous PDLIM5 Thr-290 and talin-1 Thr-2270 phosphorylation in intact cells remains unresolved.
NARROWING BIOLOGY RESIDUAL_SUBGAP
What is known: Recombinant kinase assays and double-knockout phosphoproteomics establish both sites as AAK1/BMP2K-responsive, while AAK1-specific loss and rescue establish the focal-adhesion turnover and migration phenotype.
Significance: Site-specific kinase attribution would close the causal link between AAK1's focal-adhesion recruitment, its two proposed adhesome substrates, and the nonredundant migration phenotype.
What would resolve it: Quantify both phosphosites in matched AAK1 and BMP2K single knockouts and acute degron lines, followed by wild-type, kinase-dead, and recruitment-defective rescue and focal-adhesion lifetime measurements.
Provenance (the field's own admissions):
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