GYS1

UniProt ID: P13807
Organism: Homo sapiens
Review Status: INITIALIZED
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Gene Description

GYS1 encodes glycogen synthase 1, the muscle (and general non-hepatic) isoform of glycogen synthase and the committed, rate-limiting elongation enzyme of glycogen biosynthesis. As a retaining glycosyltransferase of family GT3 (EC 2.4.1.11), it uses UDP-glucose as the glucosyl donor to add glucose units in alpha-1,4-glycosidic linkage to the non-reducing ends of a growing glycogen chain that has been primed by glycogenin (GYG1); glycogen branching enzyme (GBE1) subsequently introduces alpha-1,6 branch points. GYS1 forms a heterooctameric complex with glycogenin (a GYS1 tetramer bound to two GYG1 dimers). Its activity is tightly regulated: it is allosterically activated by glucose-6-phosphate and inhibited by hierarchical multi-site phosphorylation of its N- and C-terminal tails (by kinases including GSK3, AMPK, casein kinase 2, PASK and DYRK2), which is reversed by glycogen-associated protein phosphatase 1 (recruited by PPP1R3 targeting subunits such as PTG/PPP1R3C). GYS1 is cytosolic and associates with glycogen particles. In humans, loss-of-function variants cause muscle glycogen storage disease 0 (GSD 0b), characterized by cardiomyopathy, exercise intolerance and risk of sudden cardiac death.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0004373 alpha-1,4-glucan glucosyltransferase (UDP-glucose donor) activity
IBA
GO_REF:0000033
ACCEPT
Summary: Canonical, phylogenetically inferred molecular function of glycogen synthase: it elongates glycogen chains by transferring glucose from UDP-glucose to the alpha-1,4 non-reducing end of the polymer. This is the core catalytic activity of GYS1.
Reason: The IBA is well supported by direct experimental evidence for the human enzyme and by the biochemical literature. This is the defining activity of GYS1 (EC 2.4.1.11).
Supporting Evidence:
PMID:35835870
GYS, a retaining glycosyltransferase (GT) belonging to the GT3 superfamily, catalyzes successive addition of Ξ±-1,4-linked glucose residues to the nonreducing end of a growing polysaccharide chain, using UDP-glc as the sugar donor with the release of UDP5.
GO:0005978 glycogen biosynthetic process
IBA
GO_REF:0000033
ACCEPT
Summary: GYS1 is the elongation enzyme of glycogen biosynthesis, acting together with glycogenin (priming) and branching enzyme (branching). This is a core biological process for the gene.
Reason: Directly supported by experimental and structural work on human GYS1; the enzyme catalyzes the rate-limiting elongation step of glycogen synthesis.
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:0005737 cytoplasm
IBA
GO_REF:0000033
MODIFY
Summary: GYS1 is a cytosolic enzyme that associates with glycogen particles. Cytoplasm is correct but non-specific; cytosol (GO:0005829) is the more informative term.
Reason: Cytoplasm is correct but under-specific for this soluble, glycogen-associated enzyme. The GOA set already includes cytosol (GO:0005829) from Reactome/Ensembl, which is the more informative cellular-component assignment.
Propagation Review
Root cause: TERM SCOPING PROBLEM
Failure modes: GRANULARITY MISMATCH
Proposed replacements: cytosol
Supporting Evidence:
PMID:35835870
GYS1 is expressed in most tissues including the muscle and brain7, whereas GYS2 is expressed only in the liver.
GO:0004373 alpha-1,4-glucan glucosyltransferase (UDP-glucose donor) activity
IEA
GO_REF:0000120
ACCEPT
Summary: Electronic assignment of the canonical glycogen synthase activity, consistent with RHEA:18549 / EC 2.4.1.11 and with experimental evidence.
Reason: The IEA mapping (ARBA/RHEA/EC) matches the experimentally established catalytic activity of GYS1 and duplicates the IBA/EXP annotations to the same term.
Supporting Evidence:
PMID:35835870
GYS, a retaining glycosyltransferase (GT) belonging to the GT3 superfamily, catalyzes successive addition of Ξ±-1,4-linked glucose residues to the nonreducing end of a growing polysaccharide chain, using UDP-glc as the sugar donor with the release of UDP5.
GO:0005978 glycogen biosynthetic process
IEA
GO_REF:0000120
ACCEPT
Summary: Electronic assignment of glycogen biosynthetic process, matching the well-established role of GYS1 and duplicating the IBA/TAS/IDA annotations to the same term.
Reason: Consistent with UniPathway UPA00164 (glycogen biosynthesis) and with experimental evidence for the human enzyme.
Supporting Evidence:
PMID:35835870
Mammalian GYS is the rate-limiting enzyme in glycogen biosynthesis, and its activity is regulated posttranslationally by two mechanisms
GO:0005515 protein binding
IPI
PMID:10481074
A GSK3-binding peptide from FRAT1 selectively inhibits the G...
MARK AS OVER ANNOTATED
Summary: Bare "protein binding" IPI from an IntAct record; the recorded partner is GSK3B (UniProtKB:P49841), the kinase that phosphorylates and inhibits glycogen synthase.
Reason: Per curation guidelines, the uninformative term "protein binding" does not convey a molecular function and should not be treated as a core annotation. The underlying GYS1-GSK3B relationship (a kinase-substrate interaction) is real, but this paper is about FRAT1/GSK3 and only mentions glycogen synthase as a GSK3 substrate; a specific MF term (e.g. protein kinase binding) would be more informative if experimentally warranted for GYS1 itself.
Supporting Evidence:
PMID:10481074
FRATtide does not suppress GSK3 activity towards other
GO:0005515 protein binding
IPI
PMID:16189514
Towards a proteome-scale map of the human protein-protein in...
MARK AS OVER ANNOTATED
Summary: Bare "protein binding" IPI derived from a genome-scale yeast two-hybrid interactome map (CCSB); partner UniProtKB:O15488 (GYG2).
Reason: "protein binding" is uninformative and this is a high-throughput proteome-scale screen. The GYG2 partner is biologically plausible (glycogenin-2), but a bare binding term adds no functional information beyond the specific GYG1/GYG2 complex annotations.
Supporting Evidence:
PMID:16189514
proteome-scale map of the human protein-protein interaction network
GO:0005515 protein binding
IPI
PMID:16282323
Evidence that Ser87 of BimEL is phosphorylated by Akt and re...
MARK AS OVER ANNOTATED
Summary: Bare "protein binding" IPI; the IntAct partner is GSK3B (UniProtKB:P49841). The paper concerns Akt phosphorylation of BimEL, not GYS1 function directly.
Reason: Uninformative "protein binding" term; the source is not a study of GYS1 molecular function. Retain as over-annotation rather than a core function.
Supporting Evidence:
PMID:16282323
Ser87 of BimEL is phosphorylated by Akt
GO:0005515 protein binding
IPI
PMID:17055998
Interaction between glycogenin and glycogen synthase.
MARK AS OVER ANNOTATED
Summary: IPI recording the physiologically important GYS1-glycogenin (GYG1) interaction, established by yeast two-hybrid using human skeletal muscle. Although annotated as bare "protein binding", this partner (GYG1) is functionally central.
Reason: The interaction itself is genuine and biologically core (GYS1 forms a complex with glycogenin), but the term "protein binding" is uninformative per curation guidelines. This is better captured by the GYS1-GYG1 complex annotation (GO:1902494, part_of catalytic complex) and could support a more specific term such as glucosyltransferase/enzyme complex membership.
Supporting Evidence:
PMID:17055998
Two glycogen synthase-interacting proteins were identified in human
GO:0005515 protein binding
IPI
PMID:24165324
Leucine-rich repeat kinase 2 regulates tau phosphorylation t...
MARK AS OVER ANNOTATED
Summary: Bare "protein binding" IPI with partner GSK3B (UniProtKB:P49841); the paper is about LRRK2 activation of GSK-3beta and tau phosphorylation, not GYS1 function.
Reason: Uninformative term and not a study of GYS1 molecular function; keep as over-annotation.
Supporting Evidence:
PMID:24165324
directly associates with GSK-3Ξ²
GO:0005515 protein binding
IPI
PMID:25416956
A proteome-scale map of the human interactome network.
MARK AS OVER ANNOTATED
Summary: Bare "protein binding" IPI from a proteome-scale human interactome map (HI-II-14); partners include GYG1 and other proteins from a high-throughput screen.
Reason: Uninformative term from a large-scale interactome dataset; not a core molecular function annotation.
Supporting Evidence:
PMID:25416956
A proteome-scale map of the human interactome network
GO:0005515 protein binding
IPI
PMID:28330616
Systematic Analysis of Human Protein Phosphatase Interaction...
MARK AS OVER ANNOTATED
Summary: Bare "protein binding" IPI from a systematic phosphatase interactome study; the recorded partner is PPP1R3C/PTG (UniProtKB:Q9UQK1), a glycogen-targeting PP1 regulatory subunit relevant to GYS1 dephosphorylation.
Reason: The GYS1-PPP1R3C relationship is physiologically meaningful (PP1/PTG recruitment to glycogen dephosphorylates and thereby activates GYS1), but "protein binding" is uninformative and derives from a large affinity-proteomics survey. Keep as over-annotation; a more specific term could be warranted with dedicated evidence.
Supporting Evidence:
PMID:28330616
Yet, in contrast to kinases, much less is known about protein
GO:0005515 protein binding
IPI
PMID:28514442
Architecture of the human interactome defines protein commun...
MARK AS OVER ANNOTATED
Summary: Bare "protein binding" IPI from the BioPlex human interactome (partner PPP1R3C/Q9UQK1).
Reason: Uninformative term from a proteome-scale affinity-purification interactome; not a core molecular function.
Supporting Evidence:
PMID:28514442
Architecture of the human interactome defines protein communities
GO:0005515 protein binding
IPI
PMID:32296183
A reference map of the human binary protein interactome.
MARK AS OVER ANNOTATED
Summary: Bare "protein binding" IPI from the HuRI reference binary interactome (many partners from a single high-throughput yeast two-hybrid screen).
Reason: Uninformative term; the numerous partners recorded from this one screen are largely incidental binary hits and do not define GYS1 molecular function.
Supporting Evidence:
PMID:32296183
A reference map of the human binary protein interactome
GO:0005515 protein binding
IPI
PMID:33961781
Dual proteome-scale networks reveal cell-specific remodeling...
MARK AS OVER ANNOTATED
Summary: Bare "protein binding" IPI from BioPlex 3.0 (partners GYG2/O15488 and PPP1R3C/Q9UQK1).
Reason: Uninformative term from a proteome-scale interactome dataset; keep as over-annotation.
Supporting Evidence:
PMID:33961781
Dual proteome-scale networks reveal cell-specific remodeling of the human
GO:0005515 protein binding
IPI
PMID:35271311
OpenCell: Endogenous tagging for the cartography of human ce...
MARK AS OVER ANNOTATED
Summary: Bare "protein binding" IPI from the OpenCell endogenous-tagging interactome (partners include GYG1/GYG2).
Reason: Uninformative term from a systematic cell-organization mapping effort; not a core molecular function.
Supporting Evidence:
PMID:35271311
OpenCell: Endogenous tagging for the cartography of human cellular organization
GO:0005536 D-glucose binding
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Electronic annotation (from rat ortholog) of D-glucose binding, reflecting the substrate-binding aspect of the transferase; glucose is the moiety transferred from UDP-glucose to the growing chain.
Reason: Plausible as an aspect of the catalytic mechanism (the glucosyl donor is UDP-glucose, and glucose-6-phosphate is an allosteric activator), but this generic sugar-binding term is not the core informative molecular function, which is the glucosyltransferase activity (GO:0004373).
Supporting Evidence:
PMID:35835870
catalyzes successive addition of Ξ±-1,4-linked glucose residues to the nonreducing end of a growing polysaccharide chain, using UDP-glc as the sugar donor
GO:0005737 cytoplasm
IEA
GO_REF:0000107
MODIFY
Summary: Electronic (Ensembl ortholog) localization to cytoplasm, consistent with GYS1 being a soluble cytosolic enzyme; cytosol (GO:0005829) is the more specific term.
Reason: Cytoplasm is correct but under-specific; cytosol (GO:0005829), already present in the GOA set from Reactome/Ensembl, is the more informative assignment for this soluble glycogen-associated enzyme.
Proposed replacements: cytosol
GO:0005829 cytosol
IEA
GO_REF:0000107
ACCEPT
Summary: GYS1 acts in the cytosol, where it associates with glycogen particles. This is the correct and informative cellular-component assignment.
Reason: GYS1 has no transmembrane region or signal peptide (UniProt) and is a soluble cytosolic glycogen-synthesizing enzyme; cytosol is the appropriate location.
Supporting Evidence:
PMID:35835870
GYS1 is expressed in most tissues including the muscle and brain7, whereas GYS2 is expressed only in the liver.
GO:0005977 glycogen metabolic process
IEA
GO_REF:0000107
MODIFY
Summary: Broad electronic annotation to glycogen metabolic process; correct but a parent of the more precise glycogen biosynthetic process (GO:0005978) that also annotates GYS1.
Reason: GYS1 is specifically a biosynthetic (glycogen-synthesizing) enzyme, not a catabolic one; the more specific child term glycogen biosynthetic process (GO:0005978) is the informative annotation and is already present.
Proposed replacements: glycogen biosynthetic process
Supporting Evidence:
PMID:35835870
Mammalian GYS is the rate-limiting enzyme in glycogen biosynthesis, and its activity is regulated posttranslationally by two mechanisms
GO:0016234 inclusion body
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Electronic annotation (from mouse ortholog) placing GYS1 in inclusion bodies; likely reflects glycogen aggregates / polyglucosan (Lafora-body-type) inclusions with which the enzyme co-localizes when glycogen metabolism is perturbed, rather than a normal resident location.
Reason: Not the physiological site of action of the enzyme; a peripheral/pathology-associated localization retained as non-core rather than as a core cellular component.
Supporting Evidence:
PMID:21356517
deposits containing sparsely branched, insoluble glycogen-like polymers in many tissues, including neurons
GO:0061547 glycogen synthase activity, transferring glucose-1-phosphate
IEA
GO_REF:0000120
MARK AS OVER ANNOTATED
Summary: Electronic annotation of the glucose-1-phosphate-transferring (phosphate-incorporating) activity. Experimentally, GYS1 does introduce the beta-phosphate of UDP-glucose into glycogen, but only as a rare (~1 in 10,000 glucose) catalytic side reaction, not as a physiological function.
Reason: The phosphate-transferring activity is a documented but low-frequency "catalytic error"; presenting it as an enabled molecular function on par with the canonical GO:0004373 activity over-states its biological significance.
Supporting Evidence:
PMID:21356517
the biosynthetic enzyme glycogen synthase, which normally adds glucose residues to glycogen, is capable of incorporating
GO:0005978 glycogen biosynthetic process
TAS
Reactome:R-HSA-3322077
ACCEPT
Summary: Reactome (Glycogen synthesis) traceable assignment of glycogen biosynthetic process; consistent with the core role of GYS1.
Reason: Matches the well-established biological process for GYS1 and duplicates the IBA/IEA/IDA annotations to 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:0004373 alpha-1,4-glucan glucosyltransferase (UDP-glucose donor) activity
EXP
PMID:19699667
Identification of a novel mutation in GYS1 (muscle-specific ...
ACCEPT
Summary: Experimental (Reactome-curated) evidence for the canonical glucosyltransferase activity; this clinical study identified a homozygous GYS1 loss-of-function deletion causing muscle glycogen synthase deficiency and sudden cardiac death.
Reason: Confirms the core catalytic function of GYS1 through a loss-of-function human phenotype (GSD 0b); supports GO:0004373 as the defining activity.
Supporting Evidence:
PMID:19699667
A homozygous two base pair deletion was identified in
GO:0004373 alpha-1,4-glucan glucosyltransferase (UDP-glucose donor) activity
EXP
PMID:35835870
Molecular basis for the regulation of human glycogen synthas...
ACCEPT
Summary: Direct experimental/structural evidence for the canonical UDP-glucose-dependent alpha-1,4 glucosyltransferase activity of human GYS1, including catalytic activity (RHEA:18549), substrate binding and the catalytically competent state.
Reason: Cryo-EM and enzymatic characterization of human GYS1 directly establish this as the core molecular function.
Supporting Evidence:
PMID:35835870
resulting in a catalytically competent state for extending the associated glycogen chain
GO:0005829 cytosol
TAS
Reactome:R-HSA-3828061
ACCEPT
Summary: Reactome traceable localization to cytosol (from the "Defective GYS1" GSD 0 reaction context); consistent with GYS1 being a soluble cytosolic enzyme.
Reason: Cytosol is the correct and informative cellular component for this soluble, glycogen-associated enzyme.
GO:0005978 glycogen biosynthetic process
IDA
PMID:35835870
Molecular basis for the regulation of human glycogen synthas...
ACCEPT
Summary: ComplexPortal IDA linking the GYS1-glycogenin complex to glycogen biosynthetic process, based on the cryo-EM characterization of the human complex.
Reason: Direct experimental evidence for the involvement of GYS1 (in complex with GYG1) in glycogen biosynthesis; a core process annotation.
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: GYS1 is part of the catalytic glycogen synthase-glycogenin complex (a GYS1 tetramer with two GYG1 dimers), characterized by cryo-EM.
Reason: Direct experimental/structural evidence establishes GYS1 as a subunit of the GYS1-GYG1 catalytic complex; this is a core, biologically meaningful complex membership.
Supporting Evidence:
PMID:35835870
Cryo-EM map and model of the tetrameric GYS1–GYG1Ξ”CD complex at 3.0 Γ… resolution.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3322001
ACCEPT
Summary: Reactome traceable localization to cytosol (GYS1 polyglucosylation of oligoGlc-GYG1).
Reason: Correct informative cytosolic localization for this soluble enzyme; consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3322005
ACCEPT
Summary: Reactome traceable localization to cytosol (branch-formation reaction context with GYS1-a).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3322025
ACCEPT
Summary: Reactome traceable localization to cytosol (autoglucosylation of GYG1 complexed with GYS1-a).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3781001
ACCEPT
Summary: Reactome traceable localization to cytosol (EPM2A/laforin binding to PPP1R3C:phosphoglycogen-GYG1 complex context).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3781009
ACCEPT
Summary: Reactome traceable localization to cytosol (NHLRC1-mediated ubiquitination context).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3781018
ACCEPT
Summary: Reactome traceable localization to cytosol (EPM2A dephosphorylation of phosphoglycogen-GYG1 context).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3781023
ACCEPT
Summary: Reactome traceable localization to cytosol (PPP1R3C binding to glycogen:GYG1:GYS1 context).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3781024
ACCEPT
Summary: Reactome traceable localization to cytosol (GYS1 incorporation of phosphoglucose into glycogen-GYG1 context; the phosphate-side-reaction).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3791349
ACCEPT
Summary: Reactome traceable localization to cytosol (defective EPM2A / Lafora disease context).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3797226
ACCEPT
Summary: Reactome traceable localization to cytosol (defective NHLRC1 / Lafora disease context).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3814838
ACCEPT
Summary: Reactome traceable localization to cytosol (defective GYG1 autoglucosylation context).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0061547 glycogen synthase activity, transferring glucose-1-phosphate
EXP
PMID:21356517
Phosphate incorporation during glycogen synthesis and Lafora...
MARK AS OVER ANNOTATED
Summary: Experimental evidence that glycogen synthase (including recombinant human GYS1) can transfer the beta-phosphate of UDP-glucose into glycogen, forming glucose C2/C3 phosphomonoesters, at ~1 per 10,000 glucoses. This is the basis of the glucose-1-phosphate-transferring activity term.
Reason: The activity is experimentally real but is explicitly described as a rare deviation from the normal reaction (a "catalytic error"), not a physiological function; it should not be presented as a core enabled molecular function alongside the canonical GO:0004373 activity. Retained as an over-annotation with its supporting EXP evidence.
Supporting Evidence:
PMID:21356517
Glycogen synthase catalyzes the formation of the primary polymerizing Ξ±-1,4-glycosidic linkages by transferring a glucosyl moiety from UDP-glucose to a non-reducing end of a glycogen molecule with the release of UDP
GO:0016020 membrane
HDA
PMID:19946888
Defining the membrane proteome of NK cells.
MARK AS OVER ANNOTATED
Summary: High-throughput mass-spectrometry detection of GYS1 in a membrane-enriched fraction of an NK-cell line. GYS1 is a soluble cytosolic enzyme with no transmembrane region; the study itself notes that most non-integral hits are only transiently membrane-associated.
Reason: GYS1 has no TM domain or signal peptide (UniProt) and is established as cytosolic. Detection in a membrane proteomics fraction most likely reflects transient/peripheral association (e.g. via glycogen particles) rather than true membrane residency; this is an over-annotation from a large-scale localization screen.
Supporting Evidence:
PMID:19946888
could be predicted to be transiently associated with membranes
GO:0005829 cytosol
TAS
Reactome:R-HSA-3322003
ACCEPT
Summary: Reactome traceable localization to cytosol (autoglucosylation of GYG1 complexed with GYS1-b).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3322041
ACCEPT
Summary: Reactome traceable localization to cytosol (phosphorylated GYS1 polyglucosylation of oligoGlc-GYG1).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.
GO:0005829 cytosol
TAS
Reactome:R-HSA-3322057
ACCEPT
Summary: Reactome traceable localization to cytosol (branch formation in polyGlc-GYG1 complexed with GYS1-b).
Reason: Correct cytosolic localization, consistent with the other cytosol annotations.

Core Functions

Elongation of glycogen chains by transfer of glucose from UDP-glucose to the alpha-1,4 non-reducing end of the growing polymer (the committed, rate-limiting step of glycogen biosynthesis), acting on a glycogenin-primed chain and in concert with branching enzyme.

Supporting Evidence:
  • PMID:35835870
    GYS, a retaining glycosyltransferase (GT) belonging to the GT3 superfamily, catalyzes successive addition of Ξ±-1,4-linked glucose residues to the nonreducing end of a growing polysaccharide chain, using UDP-glc as the sugar donor with the release of UDP5.
  • PMID:35835870
    Cryo-EM map and model of the tetrameric GYS1–GYG1Ξ”CD complex at 3.0 Γ… resolution.

References

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Suggested Questions for Experts

Q: Is the glucose-1-phosphate-transferring (phosphate-incorporating) side reaction of GYS1 physiologically regulated, or is it purely a stochastic catalytic error whose rate is fixed by the enzyme mechanism?

Q: Beyond glycogenin (GYG1) and the PP1 targeting subunits (PPP1R3 family), which of the many high-throughput interactome partners of GYS1 represent bona fide regulatory or scaffolding interactions relevant to glycogen metabolism?

Suggested Experiments

Experiment: Structure-guided mutagenesis of the Glc6P allosteric arginine cluster and the N-/C-terminal phosphorylation sites in human GYS1, coupled with kinetic assays, to quantify the independent contributions of allosteric activation and dephosphorylation to activation of the human enzyme.

Experiment: Cell-based tagging/fractionation of endogenous GYS1 to test whether the reported membrane association is genuine peripheral binding (e.g. via glycogen particles) or a proteomics artifact, and to map its localization relative to glycogen synthesis sites.

πŸ“š Additional Documentation

Notes

(GYS1-notes.md)

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