HCST encodes DAP10/KAP10, a small single-pass transmembrane adaptor that forms activating receptor complexes with NKG2D/KLRK1 and additional immune receptors such as CD300H. Its cytoplasmic YINM motif is phosphorylated after receptor engagement and recruits PI3K p85 and Grb2-Vav1 signaling modules, promoting PI3K-Akt signaling, calcium mobilization, cytotoxic lymphocyte activation, and natural killer cell mediated cytotoxicity. HCST is an adaptor and substrate for phosphorylation, not a kinase.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0051897 positive regulation of phosphatidylinositol 3-kinase/protein kinase B signal transduction | IBA GO_REF:0000033 | ACCEPT | Summary: HCST/DAP10 positively regulates PI3K-Akt signaling by recruiting PI3K p85 after phosphorylation of its cytoplasmic YINM motif. Reason: This is a core pathway output of DAP10-dependent receptor signaling and is supported by both the founding DAP10 studies and the falcon review. Supporting Evidence: file:human/HCST/HCST-deep-research-falcon.md DAP10 contains a cytoplasmic YINM (YxxM-type) motif that is phosphorylated after receptor engagement. |
| GO:0005102 signaling receptor binding | IBA GO_REF:0000033 | ACCEPT | Summary: HCST/DAP10 binds signaling receptors, most prominently human NKG2D/KLRK1, through transmembrane charged-residue interactions. Reason: Signaling receptor binding is a direct molecular role of HCST in NKG2D-DAP10 receptor complex assembly. Supporting Evidence: file:human/HCST/HCST-deep-research-falcon.md NKG2D recruits its adaptor through charged residue complementarity in the transmembrane region. |
| GO:0043548 phosphatidylinositol 3-kinase binding | IBA GO_REF:0000033 | ACCEPT | Summary: PI3K binding is a direct DAP10 molecular function mediated by the phosphorylated YINM/YxxM motif. Reason: This is a specific, experimentally supported part of the HCST signaling adaptor mechanism. Supporting Evidence: PMID:10528161 KAP10, unlike other transmembrane adapter proteins, binds phosphatidylinositol-3 kinase following phosphorylation of a cytoplasmic YINM motif, which results in activation of Akt. |
| GO:0005102 signaling receptor binding | IEA GO_REF:0000002 | ACCEPT | Summary: The InterPro-derived signaling receptor binding annotation is consistent with direct experimental evidence for NKG2D and CD300H association. Reason: HCST is a transmembrane adaptor whose receptor association is a core molecular feature. Supporting Evidence: PMID:15294961 DAP10 is sufficient for human NKG2D signal transduction. |
| GO:0016020 membrane | IEA GO_REF:0000120 | MODIFY | Summary: HCST is membrane-localized, but the broad membrane term should be replaced by the more specific plasma membrane annotation already supported experimentally. Reason: HCST is a single-pass membrane protein that functions in cell-surface immune receptor complexes. Proposed replacements: plasma membrane Supporting Evidence: PMID:10426994 In natural killer (NK) and T cells, DAP10 was identified as a cell surface adaptor protein in an activating receptor complex with NKG2D. |
| GO:0043548 phosphatidylinositol 3-kinase binding | IEA GO_REF:0000002 | ACCEPT | Summary: The family-based PI3K binding annotation is supported by direct DAP10 biochemical studies. Reason: PI3K binding through the phosphorylated YINM motif is central to HCST function. Supporting Evidence: PMID:10426994 Within the DAP10 cytoplasmic domain, an Src homology 2 (SH2) domain-binding site was capable of recruiting the p85 subunit of the phosphatidylinositol 3-kinase (PI 3-kinase). |
| GO:0050776 regulation of immune response | IEA GO_REF:0000002 | MODIFY | Summary: This broad immune-response annotation is directionally correct but less useful than the specific NK-cell cytotoxicity and PI3K-Akt signaling annotations. Reason: HCST's best-supported immune process is DAP10-dependent activation of cytotoxic lymphocyte responses, including natural killer cell mediated cytotoxicity. Proposed replacements: natural killer cell mediated cytotoxicity Supporting Evidence: PMID:16582911 For full calcium release and cytotoxicity to occur, both Grb2-Vav1 and p85 had to bind to DAP10. |
| GO:0051897 positive regulation of phosphatidylinositol 3-kinase/protein kinase B signal transduction | IEA GO_REF:0000002 | ACCEPT | Summary: The InterPro-derived PI3K-Akt pathway annotation matches the established DAP10 YINM motif mechanism. Reason: DAP10 recruits PI3K p85 and activates Akt downstream of receptor engagement. Supporting Evidence: PMID:10528161 binds phosphatidylinositol-3 kinase following phosphorylation of a cytoplasmic YINM motif, which results in activation of Akt. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | MARK AS OVER ANNOTATED | Summary: The HuRI protein-binding hits are large-scale binary interactome data and do not define HCST's specific immune-receptor adaptor function. Reason: Protein binding is too generic and the listed high-throughput partners are not part of the established NKG2D/DAP10 or CD300H/DAP10 signaling mechanism. Supporting Evidence: PMID:32296183 Here we present a human 'all-by-all' reference interactome map of human binary protein interactions, or 'HuRI'. |
| GO:0005515 protein binding | IPI PMID:32814053 Interactome Mapping Provides a Network of Neurodegenerative ... | MARK AS OVER ANNOTATED | Summary: This neurodegenerative-disease interactome protein-binding annotation is not sufficient to define a core HCST function. Reason: The established function of HCST is immune receptor adaptor signaling; a generic high-throughput protein-binding annotation to a neurodegeneration interactome partner should not be treated as core function. Supporting Evidence: PMID:32814053 Interactome maps are valuable resources to elucidate protein function and disease mechanisms. |
| GO:0005886 plasma membrane | IDA PMID:15894612 The activating NKG2D receptor assembles in the membrane with... | ACCEPT | Summary: HCST/DAP10 acts in a plasma-membrane NKG2D receptor complex. Reason: The NKG2D-DAP10 hexameric signaling complex assembles in the membrane, and HCST is a single-pass membrane adaptor. Supporting Evidence: PMID:15894612 The human receptor assembles with the DAP10 signaling dimer. |
| GO:0030674 protein-macromolecule adaptor activity | IDA PMID:16582911 NKG2D-mediated signaling requires a DAP10-bound Grb2-Vav1 in... | MODIFY | Summary: The adaptor annotation is correct but can be made more specific: HCST/DAP10 is a signaling receptor complex adaptor. Reason: DAP10 links ligand-binding receptors to PI3K and Grb2-Vav1 signaling modules, which is specifically signaling receptor complex adaptor activity. Proposed replacements: signaling receptor complex adaptor activity Supporting Evidence: PMID:16582911 Human natural killer cells express NKG2D and require the transmembrane adaptor DAP10 to initiate their full cytotoxic activation. file:human/HCST/HCST-deep-research-falcon.md HCST/DAP10 is a membrane adaptor required for NKG2D signal transduction because NKG2D has a short cytoplasmic tail lacking intrinsic signaling motifs. |
| GO:0042267 natural killer cell mediated cytotoxicity | IDA PMID:16582911 NKG2D-mediated signaling requires a DAP10-bound Grb2-Vav1 in... | ACCEPT | Summary: DAP10-dependent NKG2D signaling is required for full human NK-cell cytotoxic activation. Reason: This is a core biological process for HCST in cytotoxic lymphocyte receptor signaling. Supporting Evidence: PMID:16582911 For full calcium release and cytotoxicity to occur, both Grb2-Vav1 and p85 had to bind to DAP10. |
| GO:0005515 protein binding | IPI PMID:26221034 Identification and Characterization of CD300H, a New Member ... | MODIFY | Summary: HCST/DAP10 association with CD300H is a receptor-adaptor interaction, so the generic protein binding term should be replaced by signaling receptor binding. Reason: CD300H is an immunoreceptor that associates with DAP10; the informative functional description is receptor binding/adaptor signaling rather than generic protein binding. Proposed replacements: signaling receptor binding Supporting Evidence: PMID:26221034 CD300H has a short cytoplasmic tail and associates with the signaling adaptor proteins, DAP12 and DAP10. |
| GO:0005102 signaling receptor binding | IPI PMID:15294961 A Structural basis for the association of DAP12 with mouse, ... | ACCEPT | Summary: Human NKG2D uses DAP10/HCST for signal transduction rather than DAP12. Reason: This directly supports HCST binding a signaling receptor in the human NKG2D pathway. Supporting Evidence: PMID:15294961 human NKG2D is incapable of associating with DAP12 and provide evidence that structural differences in the transmembrane of mouse and human NKG2D account for the species-specific difference for this immune receptor. |
| GO:0009986 cell surface | IDA PMID:15294961 A Structural basis for the association of DAP12 with mouse, ... | ACCEPT | Summary: HCST/DAP10 functions at the cell surface as part of NKG2D receptor complexes. Reason: Cell-surface localization is consistent with DAP10-dependent receptor-complex assembly and signaling. Supporting Evidence: PMID:10426994 DAP10 was identified as a cell surface adaptor protein in an activating receptor complex with NKG2D. |
| GO:0005886 plasma membrane | TAS Reactome:R-HSA-198983 | ACCEPT | Summary: The Reactome annotation to plasma membrane is consistent with the NKG2D-DAP10 receptor complex acting at the cell surface. Reason: HCST is a single-pass transmembrane adaptor in an activating immune receptor complex. Supporting Evidence: Reactome:R-HSA-198983 NKG2D is an activating immunoreceptor. |
| GO:0005515 protein binding | IPI PMID:10426994 An activating immunoreceptor complex formed by NKG2D and DAP... | MODIFY | Summary: The NKG2D-DAP10 interaction is real, but it should be represented as signaling receptor binding rather than generic protein binding. Reason: HCST/DAP10 binds the NKG2D signaling receptor in a functional receptor complex. Proposed replacements: signaling receptor binding Supporting Evidence: PMID:10426994 DAP10 was identified as a cell surface adaptor protein in an activating receptor complex with NKG2D. |
| GO:0009986 cell surface | IDA PMID:10426994 An activating immunoreceptor complex formed by NKG2D and DAP... | ACCEPT | Summary: HCST/DAP10 is a cell-surface adaptor in the activating NKG2D receptor complex. Reason: Cell surface is an experimentally supported location for the DAP10 receptor complex. Supporting Evidence: PMID:10426994 DAP10 was identified as a cell surface adaptor protein in an activating receptor complex with NKG2D. |
| GO:0043548 phosphatidylinositol 3-kinase binding | IDA PMID:10426994 An activating immunoreceptor complex formed by NKG2D and DAP... | ACCEPT | Summary: Direct founding evidence supports recruitment of PI3K p85 by DAP10. Reason: PI3K binding is an experimentally supported molecular function of the phosphorylated DAP10 cytoplasmic motif. Supporting Evidence: PMID:10426994 an Src homology 2 (SH2) domain-binding site was capable of recruiting the p85 subunit of the phosphatidylinositol 3-kinase (PI 3-kinase). |
| GO:0051897 positive regulation of phosphatidylinositol 3-kinase/protein kinase B signal transduction | IDA PMID:10426994 An activating immunoreceptor complex formed by NKG2D and DAP... | ACCEPT | Summary: NKG2D-DAP10 signaling activates PI3K and downstream Akt signaling. Reason: This process is a core signaling output of HCST/DAP10. Supporting Evidence: PMID:10426994 providing for NKG2D-dependent signal transduction. PMID:10528161 binds phosphatidylinositol-3 kinase following phosphorylation of a cytoplasmic YINM motif, which results in activation of Akt. |
| GO:0006468 protein phosphorylation | IGI PMID:10528161 Cutting edge: KAP10, a novel transmembrane adapter protein g... | MODIFY | Summary: The cited biology is HCST/DAP10-mediated PI3K-Akt activation after phosphorylation of the DAP10 YINM motif; the broad protein phosphorylation process term should be replaced by the specific PI3K-Akt signaling term. Reason: HCST is phosphorylated as part of receptor signaling and then recruits PI3K, so the best process-level annotation is positive regulation of PI3K/protein kinase B signal transduction, not the broad protein phosphorylation process. Proposed replacements: positive regulation of phosphatidylinositol 3-kinase/protein kinase B signal transduction Supporting Evidence: PMID:10528161 binds phosphatidylinositol-3 kinase following phosphorylation of a cytoplasmic YINM motif, which results in activation of Akt. |
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Download this section (compressed HTML)Q: Which non-NKG2D human receptors use HCST/DAP10 as a physiologically important adaptor in primary immune cells?
Q: Does HCST's Grb2-Vav1 branch or PI3K branch dominate cytotoxicity, cytokine production, and survival in different human NK and T-cell contexts?
Q: Are the high-throughput HCST interactors outside the NKG2D/CD300H receptor-signaling context reproducible at endogenous protein levels?
Experiment: CRISPR knockout and rescue of HCST in primary human NK cells using wild-type, YINM-mutant, PI3K-binding-defective, and Grb2-binding-defective DAP10 variants.
Hypothesis: Both PI3K p85 and Grb2-Vav1 recruitment to HCST are required for full NKG2D-dependent cytotoxicity.
Type: cell-based functional assay
Experiment: Endogenous co-immunoprecipitation of HCST with KLRK1 and CD300H in primary NK cells, monocytes, and myeloid dendritic cells after receptor ligation.
Hypothesis: HCST receptor-adaptor partnerships are cell-type restricted and distinguish core NKG2D signaling from non-core interactome hits.
Type: protein interaction assay
Experiment: Phosphoproteomic time course after NKG2D engagement in control and HCST-deficient human NK cells.
Hypothesis: HCST is required upstream of PI3K-Akt, Grb2-Vav1, calcium mobilization, and cytotoxicity-associated phosphorylation programs.
Type: phosphoproteomics
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