Glycogenin-1 is the self-glucosylating protein primer that initiates glycogen biosynthesis. Using UDP-alpha-D-glucose as donor and a divalent metal cofactor (Mn2+ is most effective), it autoglucosylates a specific internal tyrosine (Tyr195), forming a covalent glucose-1-O-tyrosyl linkage and building a short alpha-1,4-glucan chain of roughly 8-12 glucose residues. This maltosaccharide primer serves as the substrate onto which glycogen synthase (GYS1 in muscle and most tissues, GYS2 in liver) elongates the glycogen molecule, with glycogen branching enzyme introducing alpha-1,6 branches; glycogenin remains covalently attached at the core of the mature glycogen granule. It is a glycosyltransferase family 8 (GT8) enzyme (EC 2.4.1.186), acts in the cytosol at glycogen granules, and forms a heterooctameric complex with glycogen synthase (a GYS1 tetramer with two GYG1 dimers). Loss-of-function variants cause glycogen storage disease type XV / polyglucosan body myopathy 2, characterized by glycogen depletion and accumulation of poorly branched polyglucosan bodies in skeletal and/or cardiac muscle.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0008466 glycogenin glucosyltransferase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic (IBA) assignment of the defining molecular function of glycogenin, glycogenin glucosyltransferase activity (EC 2.4.1.186). This is the core catalytic function of GYG1 and is strongly corroborated by direct experimental evidence in human and orthologs. Reason: This is the well-established core molecular function, directly supported by crystallographic and enzymatic studies of human GYG1 and confirmed across orthologs. Supporting Evidence: PMID:22160680 Glycogenin initiates the synthesis of a maltosaccharide chain covalently attached to itself on Tyr195 via a stepwise glucosylation reaction, priming glycogen synthesis. |
| GO:0005978 glycogen biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic (IBA) assignment placing glycogenin in the glycogen biosynthetic process. Glycogenin performs the obligatory priming step of glycogen synthesis. Reason: Core biological process for GYG1; the priming reaction it catalyzes is required for glycogen synthesis. Supporting Evidence: PMID:20357282 The missense mutation resulted in inactivation of the autoglucosylation of glycogenin-1 that is necessary for the priming of glycogen synthesis in muscle. |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic (IBA) assignment that glycogenin is active in the cytoplasm. Glycogen synthesis and the self-glucosylation reaction occur in the cytosol at glycogen granules. Reason: Consistent with the cytosolic/glycogen-granule localization of glycogen metabolism; is_active_in cytoplasm correctly captures where GYG1 acts. A more specific cytosol term (GO:0005829) is also annotated by Reactome. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005634 nucleus | IEA GO_REF:0000044 | MARK AS OVER ANNOTATED | Summary: Electronic annotation to nucleus derived from UniProt Swiss-Prot subcellular location keyword mapping (SL-0191). The nuclear location in UniProt is itself an inference by similarity, with no direct experimental support for a nuclear function of GYG1. Reason: The core biology of glycogenin is cytosolic (glycogen granules). The nucleus annotation is a keyword-mapping propagation of a by-similarity UniProt entry and does not reflect an established nuclear role; it risks over-annotating GYG1 as a nuclear protein. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: Electronic annotation to cytoplasm from UniProt subcellular location keyword mapping (SL-0086). Correct and consistent with the cytosolic/glycogen-granule localization of glycogenin. Reason: Cytoplasmic localization is well established for glycogen metabolism enzymes and is consistent with the IBA and Reactome cytosol annotations. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0008466 glycogenin glucosyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Automated electronic annotation (multiple IEA methods, including ARBA and EC 2.4.1.186 mapping) of the defining glycogenin glucosyltransferase activity. Reason: Correctly assigns the core catalytic function; redundant with the experimental IDA/EXP and IBA annotations of the same term. Supporting Evidence: PMID:30356213 GYG acts as a 'seed core' for the formation of the glycogen particle by catalysing its own stepwise autoglucosylation to form a covalently bound gluco-oligosaccharide chain at initiation site Tyr 195. |
| GO:0016757 glycosyltransferase activity | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO electronic annotation from the glycosyltransferase family 8 signature (IPR002495) to the general parent term glycosyltransferase activity. Reason: Correct but general; it is the direct parent of the specific glycogenin glucosyltransferase activity (GO:0008466) that is experimentally established. Retaining the general IEA is acceptable; the specific term should be the core function. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Belongs to the glycosyltransferase 8 family. Glycogenin |
| GO:0005515 protein binding | IPI PMID:16189514 Towards a proteome-scale map of the human protein-protein in... | MARK AS OVER ANNOTATED | Summary: IntAct-curated binary interaction (from a high-throughput yeast two-hybrid interactome map) recorded with the partner GYS1 (P13807). The GO term "protein binding" is uninformative on its own. Reason: Bare "protein binding" adds no functional specificity. The biologically meaningful interaction (with glycogen synthase GYS1) is already captured by the protein homodimerization activity and catalytic-complex annotations. Per curation guidelines this uninformative term is marked as over-annotated rather than removed. Supporting Evidence: PMID:16189514 Here we describe an initial version of a proteome-scale map of human binary protein-protein interactions. |
| GO:0005515 protein binding | IPI PMID:17055998 Interaction between glycogenin and glycogen synthase. | MARK AS OVER ANNOTATED | Summary: IPI annotation to the biologically relevant GYS1 interaction (P13807), from a dedicated study mapping the glycogenin-glycogen synthase interaction to the GYG1 C-terminal 33 residues. The term "protein binding" itself is uninformative. Reason: The interaction with glycogen synthase is real and important, but the bare "protein binding" term does not convey it. The functional content (GYS1-GYG1 complex, homodimerization) is captured by more specific terms. Marked over-annotated rather than removed. Supporting Evidence: PMID:17055998 The interaction with glycogenin was found to be mediated by the region of glycogenin which contains the 33 COOH-terminal amino acid residues. |
| GO:0005515 protein binding | IPI PMID:25416956 A proteome-scale map of the human interactome network. | MARK AS OVER ANNOTATED | Summary: IntAct-curated binary interaction with GYS1 (P13807) from a proteome-scale human interactome map. Uninformative "protein binding" term. Reason: Bare "protein binding" is uninformative; the meaningful GYS1 interaction is already captured elsewhere. Marked over-annotated per guidelines rather than removed. Supporting Evidence: PMID:25416956 Combining high-quality binary pairs from the literature with systematic |
| GO:0005515 protein binding | IPI PMID:35271311 OpenCell: Endogenous tagging for the cartography of human ce... | MARK AS OVER ANNOTATED | Summary: Interaction recorded with GYS1 (P13807) from the OpenCell endogenous-tagging IP-MS interactome resource. Uninformative "protein binding" term. Reason: Bare "protein binding" is uninformative; the functionally meaningful GYS1 interaction is captured by homodimerization and complex annotations. Marked over-annotated rather than removed. Supporting Evidence: PMID:35271311 systematically map the localization and interactions of human proteins |
| GO:0005978 glycogen biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: Automated electronic annotation (multiple IEA methods, including UniPathway UPA00164) placing GYG1 in glycogen biosynthesis. Reason: Correct core biological process, redundant with the experimental and IBA annotations of the same term. Supporting Evidence: PMID:35835870 Glycogen synthesis is a multistep process consisting of a priming step by GYG followed by an elongation step carried out by GYS and then a branching step by GBE. |
| GO:0005978 glycogen biosynthetic process | TAS Reactome:R-HSA-3322077 | ACCEPT | Summary: Reactome traceable-author-statement annotation to glycogen biosynthetic process via the "Glycogen synthesis" pathway. Reason: Correctly captures the core biological process; glycogenin performs the priming step of the Reactome glycogen synthesis pathway. Supporting Evidence: PMID:35835870 Glycogen synthesis is a multistep process consisting of a priming step by GYG followed by an elongation step carried out by GYS and then a branching step by GBE. |
| GO:0008466 glycogenin glucosyltransferase activity | EXP PMID:20357282 Glycogenin-1 deficiency and inactivated priming of glycogen ... | ACCEPT | Summary: Experimental annotation of glycogenin glucosyltransferase (autoglucosylation) activity. The disease study showed unglucosylated glycogenin-1 in patient muscle and that the Thr83Met variant inactivates autoglucosylation. Reason: Directly supports the core catalytic function; the loss of this activity in the Thr83Met patient causally links the enzyme activity to glycogen synthesis priming. Supporting Evidence: PMID:20357282 The missense mutation resulted in inactivation of the autoglucosylation of glycogenin-1 that is necessary for the priming of glycogen synthesis in muscle. |
| GO:0005978 glycogen biosynthetic process | IDA PMID:35835870 Molecular basis for the regulation of human glycogen synthas... | ACCEPT | Summary: ComplexPortal IDA annotation placing the GYS1-GYG1 complex in glycogen biosynthesis, based on the cryo-EM structural study of the glycogen synthase-glycogenin complex. Reason: Core biological process, supported by structural characterization of the functional biosynthetic complex. Supporting Evidence: PMID:35835870 Glycogen synthesis is a multistep process consisting of a priming step by GYG followed by an elongation step carried out by GYS and then a branching step by GBE. |
| GO:1902494 catalytic complex | IDA PMID:35835870 Molecular basis for the regulation of human glycogen synthas... | ACCEPT | Summary: ComplexPortal IDA annotation that GYG1 is part of a catalytic complex, based on the cryo-EM structure of the tetrameric GYS1-GYG1 complex (the glycogen synthase-glycogenin complex, ComplexPortal CPX-26491). Reason: Well supported; GYG1 is an integral subunit of the glycogen synthase-glycogenin biosynthetic complex, a catalytic complex. Supporting Evidence: PMID:35835870 Cryo-EM map and model of the tetrameric GYS1βGYG1ΞCD complex at 3.0 Γ
resolution. |
| GO:0005978 glycogen biosynthetic process | IMP PMID:22160680 Conformational plasticity of glycogenin and its maltosacchar... | ACCEPT | Summary: IMP annotation to glycogen biosynthetic process based on the structural and mutational study showing the GSD XV Thr83Met variant is conformationally locked and catalytically inactive, impairing glycogen synthesis priming. Reason: The disease-causing loss-of-function mutation directly links GYG1 to the glycogen biosynthetic process (priming step). Supporting Evidence: PMID:22160680 The Thr83Met mutation, which causes glycogen storage disease XV, is conformationally locked in the ground state and catalytically inactive. |
| GO:0005634 nucleus | ISS GO_REF:0000024 | MARK AS OVER ANNOTATED | Summary: Sequence-similarity (ISS) annotation to nucleus transferred from an ortholog (P13280). As with the SubCell IEA nucleus annotation, there is no direct experimental support for a nuclear function of GYG1. Reason: The core localization and function of glycogenin are cytosolic (glycogen granules). The nucleus annotation is an inference by similarity without experimental support and risks over-annotating a nuclear role. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005737 cytoplasm | ISS GO_REF:0000024 | ACCEPT | Summary: Sequence-similarity (ISS) annotation to cytoplasm transferred from an ortholog (P13280). Consistent with the established cytosolic localization of glycogenin. Reason: Cytoplasmic localization is correct and well supported for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005737 cytoplasm | ISS GO_REF:0000024 | ACCEPT | Summary: Sequence-similarity (ISS) annotation that glycogenin is active in the cytoplasm, transferred from an ortholog (C4R941). Consistent with where the priming reaction occurs. Reason: Correctly captures that GYG1 acts in the cytoplasm (at glycogen granules). Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Cytosolic localization |
| GO:0008466 glycogenin glucosyltransferase activity | IDA PMID:22160680 Conformational plasticity of glycogenin and its maltosacchar... | ACCEPT | Summary: Direct experimental (IDA) annotation of glycogenin glucosyltransferase activity from crystallographic snapshots of human glycogenin captured during its reaction cycle with UDP-glucose, Mn2+ and its maltosaccharide substrate. Reason: Direct structural/enzymatic evidence for the core catalytic function in human GYG1. Supporting Evidence: PMID:22160680 Glycogenin initiates the synthesis of a maltosaccharide chain covalently attached to itself on Tyr195 via a stepwise glucosylation reaction, priming glycogen synthesis. |
| GO:0008466 glycogenin glucosyltransferase activity | IDA PMID:30356213 Palladium-mediated enzyme activation suggests multiphase ini... | ACCEPT | Summary: Direct experimental (IDA) annotation of glycogenin glucosyltransferase activity from a study that accessed homogeneous glucosylated states of GYG via palladium-mediated activation and characterized catalytic activity at distinct stages of autoglucosylation. Reason: Direct enzymatic evidence for the core catalytic function. Supporting Evidence: PMID:30356213 GYG acts as a 'seed core' for the formation of the glycogen particle by catalysing its own stepwise autoglucosylation to form a covalently bound gluco-oligosaccharide chain at initiation site Tyr 195. |
| GO:0030145 manganese ion binding | IDA PMID:22160680 Conformational plasticity of glycogenin and its maltosacchar... | ACCEPT | Summary: Direct experimental (IDA) annotation of manganese ion binding, from crystal structures of human glycogenin in complex with manganese, UDP and UDP-alpha-D-glucose. Mn2+ is the catalytic cofactor coordinating the sugar donor. Reason: Well supported; Mn2+ binding is a genuine, structurally defined cofactor requirement for the autoglucosylation reaction. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Required for self-glucosylation. Manganese is |
| GO:0030145 manganese ion binding | IDA PMID:30356213 Palladium-mediated enzyme activation suggests multiphase ini... | ACCEPT | Summary: Direct experimental (IDA) annotation of manganese ion binding from crystal structures of human glycogenin (residues 1-262) in complex with UDP and manganese. Reason: Well supported cofactor requirement; redundant with the PMID:22160680 IDA annotation of the same term. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Required for self-glucosylation. Manganese is |
| GO:0042803 protein homodimerization activity | IDA PMID:22160680 Conformational plasticity of glycogenin and its maltosacchar... | ACCEPT | Summary: Direct experimental (IDA) annotation of protein homodimerization activity. Glycogenin functions as a dimer; the crystallographic study characterized inter- and intra-subunit modes of glucosylation dependent on the dimeric arrangement. Reason: Well supported; GYG1 forms homodimers, and the dimer is functionally relevant to its intersubunit glucosylation mechanism and to the GYS1-GYG1 heterooctamer (two GYG1 dimers). Supporting Evidence: PMID:22160680 The rearranged lid guides the nascent maltosaccharide chain into the |
| GO:0042803 protein homodimerization activity | IDA PMID:30356213 Palladium-mediated enzyme activation suggests multiphase ini... | ACCEPT | Summary: Direct experimental (IDA) annotation of protein homodimerization activity from the structural study of homogeneously glucosylated GYG states. Reason: Well supported homodimerization; redundant with the PMID:22160680 IDA annotation of the same term. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt 2 dimers of GYG1 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-9036727 | MARK AS OVER ANNOTATED | Summary: Reactome TAS annotation placing GYG1 in the lysosomal lumen, arising from its appearance in the "GAA hydrolyzes lysosomal glycogen" reaction (Pompe disease / lysosomal glycogen degradation pathway) where glycogen (with its glycogenin core) is transported to the lysosome. Reason: This is a pathway-context localization; glycogenin appears in the lysosome only as the buried core of glycogen delivered for lysosomal degradation, not as a lysosomal-lumen-resident protein with a lysosomal function. The core localization of GYG1 is cytosolic (glycogen granules). Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-9036729 | MARK AS OVER ANNOTATED | Summary: Reactome TAS annotation to lysosomal lumen from the "Defective GAA does not hydrolyze lysosomal glycogen" reaction (Pompe disease). Same pathway-context artifact as the R-HSA-9036727 annotation. Reason: Pathway-context localization reflecting glycogen (with its glycogenin core) delivered to the lysosome; not a resident lysosomal-lumen protein. Core localization is cytosolic. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005576 extracellular region | TAS Reactome:R-HSA-6798748 | MARK AS OVER ANNOTATED | Summary: Reactome TAS annotation to extracellular region from the "Exocytosis of secretory granule lumen proteins" reaction (neutrophil degranulation pathway), in which GYG1 was detected in neutrophil granule proteomes. Reason: This localization derives from GYG1's incidental detection in neutrophil degranulation/secretory-granule proteomics and does not reflect an extracellular function. Glycogenin is a cytosolic glycogen-priming enzyme. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005576 extracellular region | TAS Reactome:R-HSA-6800434 | MARK AS OVER ANNOTATED | Summary: Reactome TAS annotation to extracellular region from the "Exocytosis of ficolin-rich granule lumen proteins" reaction (neutrophil degranulation pathway). Reason: Same neutrophil-degranulation pathway-context artifact; does not reflect an extracellular function of glycogenin. Core localization is cytosolic. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0034774 secretory granule lumen | TAS Reactome:R-HSA-6798748 | MARK AS OVER ANNOTATED | Summary: Reactome TAS annotation to secretory granule lumen from the neutrophil degranulation pathway, based on detection of GYG1 in secretory granule proteomes. Reason: Pathway-context localization from neutrophil granule proteomics; not the core cytosolic localization or function of glycogenin. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:1904813 ficolin-1-rich granule lumen | TAS Reactome:R-HSA-6800434 | MARK AS OVER ANNOTATED | Summary: Reactome TAS annotation to ficolin-1-rich granule lumen from the neutrophil degranulation pathway. Reason: Pathway-context localization from neutrophil granule proteomics; not the core cytosolic localization or function of glycogenin. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0016020 membrane | HDA PMID:19946888 Defining the membrane proteome of NK cells. | MARK AS OVER ANNOTATED | Summary: High-throughput direct assay (HDA) annotation to membrane, from a mass spectrometry study of the membrane proteome of an NK-like cell line in which GYG1 was among identified proteins. Reason: The study itself notes that many identified species are proteins transiently associated with membranes rather than integral membrane proteins. Glycogenin has no transmembrane region and is a soluble cytosolic/glycogen-granule protein; the membrane co-fractionation is not evidence of a membrane localization function. Supporting Evidence: PMID:19946888 The remaining species were largely involved in cellular processes and molecular functions that could be predicted to be transiently associated with membranes. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3322001 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "GYS1 catalyzes the polyglucosylation of oligoGlc-GYG1" reaction of glycogen synthesis. Correctly localizes GYG1 to the cytosol. Reason: Cytosol is the correct core cellular location for glycogenin and glycogen synthesis. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3322005 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "GBE1 catalyzes branch formation in polyGlc-GYG1 complexed with GYS1-a" reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen biosynthesis. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3322041 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "Phosphorylated GYS1 catalyzes the polyglucosylation of oligoGlc-GYG1" reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen biosynthesis. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3322057 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "GBE1 catalyzes branch formation in polyGlc-GYG1 complexed with GYS1-b" reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen biosynthesis. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-71552 | ACCEPT | Summary: Reactome TAS annotation to cytosol from a glycogenin/glycogen limit-dextrin reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-71593 | ACCEPT | Summary: Reactome TAS annotation to cytosol from a glycogenin poly-glucosyl reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3322003 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "Autoglucosylation of GYG1 complexed with GYS1-b" reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for the autoglucosylation reaction. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3322025 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "Autoglucosylation of GYG1 complexed with GYS1-a" reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for the autoglucosylation reaction. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3781001 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "EPM2A dimer binds PPP1R3C:phosphoglycogen-GYG1 complex" reaction (Lafora disease pathway). Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3781009 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "NHLRC1 mediated ubiquitination of EPM2A and PPP1RC3 associated with glycogen-GYG1" reaction (Lafora disease pathway). Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3781018 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "EPM2A dimer dephosphorylates phosphoglycogen-GYG1" reaction (Lafora disease pathway). Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3781023 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "PPP1R3C binds to glycogen:GYG1:GYS1" reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3781024 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "GYS1 catalyzes the incorporation of phosphoglucose into glycogen-GYG1" reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3791349 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "Defective EPM2A does not dephosphorylate phosphoglycogen (type 2A disease)" reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3797226 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "Defective NHLRC1 does not ubiquitinate EPM2A (laforin) and PPP1R3C (PTG) (type 2B disease)" reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3814838 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "Defective GYG1 is not autoglucosyolated" reaction (glycogen storage disease type XV pathway). Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for the autoglucosylation reaction. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3828061 | ACCEPT | Summary: Reactome TAS annotation to cytosol from the "Defective GYS1 does not transfer glucose to growing glycogen chains" reaction. Correct cytosolic localization. Reason: Cytosol is the correct core cellular location for glycogen metabolism. Supporting Evidence: file:human/GYG1/GYG1-uniprot.txt Localizes to glycogen granules |
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Download this section (compressed HTML)Q: What determines the final length (~8-12 residues) of the self-glucosylated primer before handoff to glycogen synthase, and how is the transition between glycogenin priming and glycogen synthase elongation regulated?
Q: Does GYG1 have any physiologically relevant function outside the cytosolic glycogen granule (e.g. the reported nuclear localization by similarity)?
Experiment: Quantitative reconstitution of primer chain-length distribution and GYG1-to-GYS1 handoff kinetics using the homogeneously glucosylated GYG1 intermediates.
Experiment: Structural and functional characterization of additional disease variants (beyond Thr83Met, Ala16Pro, Asp102His) to map genotype-phenotype relationships for GSD XV versus PGBM2.
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