Ctns encodes cystinosin, a lysosomal membrane transporter that exports cystine for cytosolic cysteine metabolism. In the Drosophila fat body, lysosomal cystine mobilization during fasting supports metabolic adaptation and modulates TORC1 reactivation and autophagy. Loss of Ctns causes cystine accumulation and heightened starvation sensitivity.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003333 amino acid transmembrane transport | ISS PMID:17443808 A screen for neurotransmitter transporters expressed in the ... | MODIFY | Summary: Cystine specifies the broad amino acid transport annotation. Reason: Endogenous lysosomal localization, cystine accumulation in dCTNS mutants and transport-dependent starvation rescue identify cystine as the physiologically relevant substrate. The broad annotation is sound but does not express this experimentally established specificity. Proposed replacements: L-cystine transport Supporting Evidence: PMID:35175796 dCTNS−/− larvae showed accumulation of cystine PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0005765 lysosomal membrane | IBA GO_REF:0000033 | ACCEPT | Summary: Cystinosin acts in the lysosomal membrane. Reason: Endogenous tagging of the fly ortholog provides direct lysosomal localization, and transport-dependent phenotypes tie this compartment to its physiological function. Supporting Evidence: PMID:35175796 Endogenous tagging of the Drosophila ortholog CG17119 (hereafter referred to as dCTNS) confirmed its specific lysosomal localization in cells of the fat body PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0005765 lysosomal membrane | IEA GO_REF:0000120 | ACCEPT | Summary: Cystinosin acts in the lysosomal membrane. Reason: Endogenous tagging of the fly ortholog provides direct lysosomal localization, and transport-dependent phenotypes tie this compartment to its physiological function. Supporting Evidence: PMID:35175796 Endogenous tagging of the Drosophila ortholog CG17119 (hereafter referred to as dCTNS) confirmed its specific lysosomal localization in cells of the fat body PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0005765 lysosomal membrane | IMP PMID:35175796 Lysosomal cystine mobilization shapes the response of TORC1 ... | ACCEPT | Summary: Cystinosin acts in the lysosomal membrane. Reason: Endogenous tagging of the fly ortholog provides direct lysosomal localization, and transport-dependent phenotypes tie this compartment to its physiological function. Supporting Evidence: PMID:35175796 Endogenous tagging of the Drosophila ortholog CG17119 (hereafter referred to as dCTNS) confirmed its specific lysosomal localization in cells of the fat body PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0005765 lysosomal membrane | ISS GO_REF:0000024 | ACCEPT | Summary: Cystinosin acts in the lysosomal membrane. Reason: Endogenous tagging of the fly ortholog provides direct lysosomal localization, and transport-dependent phenotypes tie this compartment to its physiological function. Supporting Evidence: PMID:35175796 Endogenous tagging of the Drosophila ortholog CG17119 (hereafter referred to as dCTNS) confirmed its specific lysosomal localization in cells of the fat body PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0015171 amino acid transmembrane transporter activity | ISS PMID:17443808 A screen for neurotransmitter transporters expressed in the ... | MODIFY | Summary: Cystine specifies the broad amino acid transporter activity annotation. Reason: Endogenous lysosomal localization, cystine accumulation in dCTNS mutants and transport-dependent starvation rescue identify cystine as the physiologically relevant substrate. The broad annotation is sound but does not express this experimentally established specificity. Proposed replacements: L-cystine transmembrane transporter activity Supporting Evidence: PMID:35175796 dCTNS−/− larvae showed accumulation of cystine PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0015179 L-amino acid transmembrane transporter activity | IEA GO_REF:0000117 | MODIFY | Summary: Cystine specifies the broad L-amino acid transporter activity annotation. Reason: Endogenous lysosomal localization, cystine accumulation in dCTNS mutants and transport-dependent starvation rescue identify cystine as the physiologically relevant substrate. The broad annotation is sound but does not express this experimentally established specificity. Proposed replacements: L-cystine transmembrane transporter activity Supporting Evidence: PMID:35175796 dCTNS−/− larvae showed accumulation of cystine PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0015184 L-cystine transmembrane transporter activity | IBA GO_REF:0000033 | ACCEPT | Summary: Lysosomal cystine export is the core transporter activity. Reason: Cystine accumulation after dCTNS loss, depletion of cysteine during fasting and rescue by bypassing lysosomal cystine export support the cystine transport mechanism in flies. Supporting Evidence: PMID:35175796 dCTNS−/− larvae showed accumulation of cystine PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0015184 L-cystine transmembrane transporter activity | IMP PMID:35175796 Lysosomal cystine mobilization shapes the response of TORC1 ... | ACCEPT | Summary: Lysosomal cystine export is the core transporter activity. Reason: Cystine accumulation after dCTNS loss, depletion of cysteine during fasting and rescue by bypassing lysosomal cystine export support the cystine transport mechanism in flies. Supporting Evidence: PMID:35175796 dCTNS−/− larvae showed accumulation of cystine PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0015184 L-cystine transmembrane transporter activity | ISS GO_REF:0000024 | ACCEPT | Summary: Lysosomal cystine export is the core transporter activity. Reason: Cystine accumulation after dCTNS loss, depletion of cysteine during fasting and rescue by bypassing lysosomal cystine export support the cystine transport mechanism in flies. Supporting Evidence: PMID:35175796 dCTNS−/− larvae showed accumulation of cystine PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0015811 L-cystine transport | ISS GO_REF:0000024 | ACCEPT | Summary: Cystine transport is a direct biological role. Reason: The fly loss-of-function and transport-dependent rescue experiments establish lysosomal cystine mobilization, beyond sequence similarity alone. Supporting Evidence: PMID:35175796 dCTNS−/− larvae showed accumulation of cystine PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:0034486 vacuolar transmembrane transport | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Vacuolar transport is a valid broad parent of lysosomal cystine transport. Reason: Cystinosin mediates export from the lysosome, a vacuolar compartment; the specific lysosomal cystine process better describes the core function. Supporting Evidence: PMID:35175796 Endogenous tagging of the Drosophila ortholog CG17119 (hereafter referred to as dCTNS) confirmed its specific lysosomal localization in cells of the fat body PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:1904919 L-cystine transmembrane transport from lysosomal lumen to cytosol | IEA GO_REF:0000117 | ACCEPT | Summary: The transporter mobilizes cystine from the lysosomal lumen into the cytosol. Reason: The fly study directly couples lysosomal cystine export to cytosolic cysteine metabolism during fasting; mutant cystine accumulation and bypass rescue establish the transport direction physiologically. Supporting Evidence: PMID:35175796 Endogenous tagging of the Drosophila ortholog CG17119 (hereafter referred to as dCTNS) confirmed its specific lysosomal localization in cells of the fat body PMID:35175796 dCTNS−/− larvae showed accumulation of cystine PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
| GO:1904919 L-cystine transmembrane transport from lysosomal lumen to cytosol | IMP PMID:35175796 Lysosomal cystine mobilization shapes the response of TORC1 ... | ACCEPT | Summary: The transporter mobilizes cystine from the lysosomal lumen into the cytosol. Reason: The fly study directly couples lysosomal cystine export to cytosolic cysteine metabolism during fasting; mutant cystine accumulation and bypass rescue establish the transport direction physiologically. Supporting Evidence: PMID:35175796 Endogenous tagging of the Drosophila ortholog CG17119 (hereafter referred to as dCTNS) confirmed its specific lysosomal localization in cells of the fat body PMID:35175796 dCTNS−/− larvae showed accumulation of cystine PMID:35175796 The role of dCTNS during starvation was dependent on its cystine transport function |
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