GBE1

Summary: Specify the established glucan branching activity.

Reason: The InterPro mapping correctly identifies an enzyme, but catalytic activity is much less informative than the demonstrated GBE1 reaction. Human enzyme experiments establish alpha-glucan branching, and GO:0003844 is an is_a descendant of GO:0003824. Refine to the already asserted specific activity without treating the broad mapping as false.

Proposed replacements: 1,4-alpha-glucan branching enzyme activity

Summary: Human wild-type enzyme activity was measured against mutant and mock controls.

Reason: The original COS-7 expression experiments directly compared human wild-type and variant GBE1 using a phosphorylase-coupled branching assay. These measurements support the specific activity; variant-dependent residual activity does not change the normal enzyme assignment.

Summary: Ancestral branching activity is supported on the human lineage.

Reason: The actual PANTHER family tree places human Q04446 below the branching-activity IBD at PTN000040010, with no intervening target-path loss. The human experimental annotation in the descendant evidence is legitimate grounding, not circular transfer. Direct human functional work independently supports this defining activity.

Summary: Human GBE1 has glucan branching activity.

Reason: The structural and functional study supports the human branching enzyme. Its crystallized 38–700 construct is engineered and is not a separate natural product. The observed sugar pocket and modeled catalytic-site binding are distinguished in the source assessment; neither distinction undermines the established branching reaction.

Summary: The combined electronic mapping identifies the correct specific enzyme activity.

Reason: The EC, family and orthology-based sources converge on the reaction directly established for human GBE1: transfer of a terminal alpha-1,4-linked glucan segment to create an alpha-1,6 branch. Acceptance rests on the experimentally supported target function, without claiming that every individual rule branch was experimentally tested.

Summary: The cited functional study supports the normal branching reaction.

Reason: This traceable statement cites the same human functional study that directly measures branching activity. It is consistent with the enzyme’s normal function. The distinct EXP and TAS source contexts are retained rather than collapsing them into one assertion.

Summary: Normal GBE1 branching is established despite the disease-model provenance.

Reason: R-HSA-3878762 is explicitly a failed reaction containing F257L/R515C GBE1, not evidence that those variants perform a normal reaction. Its normalReaction link leads to R-HSA-3322016, whose catalyst resolves to human Q04446 and GO:0003844. Together with direct human assays, this supports the gene-level normal activity while preserving the disease source and mutant limitation.

Summary: A glycoside-hydrolase family assignment overstates the demonstrated reaction.

Reason: GBE1 cleaves and transfers a glucan segment during branching, but the established net reaction uses a glucan 6-hydroxyl acceptor. The structural paper distinguishes this from an amylase reaction using water. Its description of an initial hydrolytic step does not demonstrate a separate water-acceptor hydrolase activity. The inspected evidence therefore does not justify the broad hydrolytic activity transferred from IPR004193; this is not a claim that all possible side hydrolysis has been excluded.

Summary: The STBD1 association is real, but generic protein binding is uninformative.

Reason: The original study directly reports co-immunoprecipitation of tagged GBE1 and STBD1. STBD1 is a glycogen-autophagy cargo receptor, not thereby a signaling receptor. Later recruitment and deprivation experiments in this paper concern other glycogen enzymes and do not establish a corresponding GBE1 mechanism. Retain the positive association as evidence while removing the uninformative generic binding annotation; no supported specific GBE1 activity replacement was identified.

Summary: The positive NSP16 interaction can be represented as enzyme binding.

Reason: GBE1–NSP16 is positive in the retested HIS3 workflow; the complementary GFP configuration and inspected N2H table provide no target confirmation. Independently established NSP16 methyltransferase identity supports enzyme binding, without transferring catalysis or viral physiology to GBE1. STBD1 co-immunoprecipitation also remains positive; the different action reflects the availability of an informative binding class, not an assay-confidence ranking.

Proposed replacements: enzyme binding

Summary: Retain the valid cytoplasmic ancestry and specify the cytosol.

Reason: The cytoplasm IBD at PTN000040010 is a valid ancestral placement for the actual human lineage, with no observed target-path loss. Independent target-specific Reactome entities place human GBE1 in the cytosol, which is part_of cytoplasm. Refinement improves location precision; it is not a phylogenetic failure or a donor-count objection.

Proposed replacements: cytosol

Summary: Specify cytosol without claiming a newly inspected yeast localization assay.

Reason: The yeast P32775 transfer supports a broad cytoplasmic location. The underlying donor experiment was not independently read here, so no donor-specific assay detail or error is asserted. Independent human GBE1 catalyst records support cytosol, a part_of refinement of cytoplasm, for the unqualified gene-level location.

Proposed replacements: cytosol

Summary: The combined electronic cytosolic assignment is consistent with the human catalyst.

Reason: The electronic source context is corroborated by the normal human Q04446 catalyst explicitly located in cytosol in glycogen-branching reactions. This is the compartment of the primary enzyme activity, while urinary-vesicle detection is retained as a separate occurrence context.

Summary: The GYG1/GYS1 branching model explicitly places human GBE1 in cytosol.

Reason: The actual R-HSA-3322005 catalyst chain resolves to Q04446 residues 1–702 with GO:0005829 as its compartment. This is a target-level curated model assertion, not an independently inspected microscopy experiment or a transfer of the substrate’s compartment to an unidentified protein.

Summary: The normal branch-forming catalyst is explicitly cytosolic.

Reason: R-HSA-3322016 uses catalyst 71577 and physical entity 71576, whose reference entity is human Q04446 and whose compartment is cytosol. The explicit target membership supports this location with the model’s evidential scope retained.

Summary: The second normal branching context uses the same cytosolic human catalyst.

Reason: R-HSA-3322057 independently names the GBE1 catalyst chain that resolves to human Q04446 in GO:0005829. The model supports the enzyme’s normal cytosolic location; it does not add an independently read localization assay.

Summary: The disease model preserves cytosolic GBE1 identity without proving mutant activity.

Reason: R-HSA-3878762 contains explicit human GBE1 variant entities in cytosol and links to the normal reaction R-HSA-3322016. Both the literal mutant compartment and the normal target catalyst support this gene-level cytosolic assertion. Failed catalysis is not treated as absence of the protein or as a new localization experiment.

Summary: Refine carbohydrate metabolism to the established glycogen biosynthetic step.

Reason: The domain mappings correctly associate GBE1 with carbohydrate metabolism. Human GBE1 performs the branching step in glycogen synthesis, and GO:0005978 has verified is_a ancestry to GO:0005975. The specific process is already asserted and describes the product’s direct catalytic work.

Proposed replacements: glycogen biosynthetic process

Summary: Specify glycogen biosynthesis within glycogen metabolism.

Reason: The cited human enzyme study supports the branching reaction that constructs glycogen. GO:0005978 is an is_a child of glycogen metabolic process and is already asserted for this gene. Refinement makes the supported synthetic role explicit without denying the broader metabolic claim.

Proposed replacements: glycogen biosynthetic process

Summary: The ancestral glycogen biosynthetic role is retained in human GBE1.

Reason: The actual target lineage descends from the glycogen-biosynthesis IBD at PTN000040012, with no target-path negative placement. Human catalytic evidence shows that GBE1 itself builds glucan branch points, so this is participation in glycogen biosynthesis rather than a requirement inferred only from disease.

Summary: GBE1 directly contributes the branch-forming chemistry of glycogen synthesis.

Reason: The human structural and functional study concerns the enzyme that constructs alpha-1,6 branches in glycogen. The engineered crystallization construct and modeled active-site interpretation are bounded separately; the biosynthetic assignment rests on established branch-forming chemistry.

Summary: The electronic glycogen biosynthesis assignment matches direct target function.

Reason: The combined rule, orthology, family and pathway mapping agrees with the human enzyme’s demonstrated branch-forming step in glycogen production. This acceptance does not depend on inferring the content of an inaccessible individual pathway mapping or on assigning a new process from a disease phenotype.

Summary: The glycogen-synthesis pathway contains an explicit human GBE1 catalyst.

Reason: R-HSA-3322077 contains normal branch-forming reactions whose catalyst chain resolves through 71577 and 71576 to human Q04446. GBE1 is the catalyst of a construction step, not merely a member of a pathway-wide input set. This model supports the already experimentally established glycogen biosynthetic role.

Summary: Refine the genuine energy-metabolism ancestor to glycogen biosynthesis.

Reason: GO:0005978 has an actual is_a path through glycogen metabolism, energy reserve metabolism and energy derivation to GO:0006091. The broad term is therefore compatible with GBE1; it is not refuted because the reaction stores rather than releases energy. The cited enzyme study supports the more informative, already asserted glycogen biosynthetic process.

Proposed replacements: glycogen biosynthetic process

Summary: A specific basis for the cation-binding inference remains unresolved.

Reason: The current IPR006048 entry maps this domain to cation binding, but describes calcium sites in the inserted loop of alpha-amylases rather than a human GBE1 binding assay. The human UniProt entry lists structures 4BZY, 5CLT and 5CLW, carbohydrate BINDING features and no metal-binding keyword or cofactor statement. Selected human structural Results and Methods do not establish the cation-binding basis of this inference. These checks do not demonstrate absence of binding, and no independent coordinate audit or metal-binding experiment was performed. Retain UNDECIDED while the mapping evidence is unresolved.

Summary: GBE1 was identified in a urinary-exosome preparation.

Reason: The original NHLBI target table lists GBE1/NP_000149 with one peptide assigned to source 2, PMID:19056867. This supports occurrence in the analyzed urinary-vesicle preparation, with the literal urine extension retained. The identification does not establish vesicle topology, a secretion mechanism, a present-day isoform or extracellular enzyme function.

Summary: A second urinary-vesicle study directly identifies GBE1.

Reason: The original supplementary table lists Q04446/GBE1 with two unique peptides in each of the two noncancer-pool analyses. These are duplicate analyses of a pooled preparation, not independent donor replications. The target-level evidence supports non-core vesicle-fraction occurrence, while contamination, topology and physiological-function limits remain; zero values in the other pool do not establish disease-specific absence.

Summary: A separate noncatalytic pocket directly binds an oligosaccharide.

Reason: Human GBE1 residues 38–700 were crystallized with maltoheptaose at a cleft separate from the catalytic center. This directly supports oligosaccharide binding beyond the implicit substrate recognition of branching activity. Contacts to the final three glucose units involve crystal packing; glycogen-granule anchoring and a molecular-ruler role remain proposed. No natural truncated product, measured glycogen affinity or additional process is asserted.