GLB1 encodes lysosomal beta-galactosidase, which removes terminal beta-linked galactose from glycoconjugates, including gangliosides, glycoprotein-derived glycans and keratan sulfate. The active enzyme undergoes lysosomal maturation and associates with a multienzyme system containing protective protein cathepsin A and neuraminidase. Deficiency causes GM1 gangliosidosis or Morquio B disease. Alternative splicing also produces the shorter, catalytically inactive S-Gal/elastin-binding protein, which binds extracellular-matrix ligands and supports elastic-fiber deposition. These activities belong to distinct GLB1 products.
Curated functional classes representing distinct biological activities. These may be splice variants, cleavage products, or other forms with different functions.
GLB1_LYSOSOMALGLB1_SGAL| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004553 hydrolase activity, hydrolyzing O-glycosyl compounds | IEA GO_REF:0000002 | TOO GENERAL | Summary: GLB1 catalysis is specifically beta-galactosidase activity. Reason: The accepted beta-galactosidase activity entails this O-glycosyl-hydrolase ancestor. The term adds no functional resolution; the electronic inference is not being called false. |
| GO:0004565 beta-galactosidase activity | IBA GO_REF:0000033 | ACCEPT | Summary: The canonical human enzyme retains ancestral beta-galactosidase activity. Reason: The actual PAINT assertion is at AN0/PTN000602923, ancestral to the exact human677-residue leaf AN156. The selected catalytic columns retain the relevant glutamates, and direct human biochemical evidence agrees. The target's own experimental evidence legitimately contributes to the ancestral assertion. This entry-level inference does not establish activity for the divergent elastin-binding isoform. |
| GO:0004565 beta-galactosidase activity | IEA GO_REF:0000120 | ACCEPT | Summary: The electronic beta-galactosidase assignment agrees with direct human evidence. Reason: The combined EC, family and orthology mappings describe the active lysosomal product. They do not establish catalytic activity for every alternative product. |
| GO:0004565 beta-galactosidase activity | IDA PMID:11927518 Endothelial cell senescence in human atherosclerosis: role o... | ACCEPT | Summary: Endothelial senescence-associated staining reports beta-galactosidase activity. Reason: The original abstract documents the staining in human vascular endothelial material. Preserve both the aortic-endothelial-cell and cytoplasm extension atoms. Cytoplasm includes lysosomes; the context is not a cytosolic-enzyme assertion. The assay does not show that GLB1 drives senescence. Supporting Evidence: PMID:11927518 beta-gal stained cells are vascular endothelial cells. |
| GO:0004565 beta-galactosidase activity | EXP PMID:15714521 Role of beta-galactosidase and elastin binding protein in ly... | ACCEPT | Summary: Human GLB1 variants inform the established catalytic function. Reason: The study examines beta-galactosidase deficiency and variant effects. Retain activity for the lysosomal product while distinguishing the separately discussed elastin-binding product; neither mutant loss nor elastic-fiber phenotypes confer catalysis on that shorter product. Supporting Evidence: PMID:15714521 the identified mutations affect GLB1 enzyme activity and/or stability |
| GO:0004565 beta-galactosidase activity | EXP PMID:19472408 GM1 gangliosidosis and Morquio B disease: expression analysi... | ACCEPT | Summary: Variant expression experiments support beta-galactosidase activity. Reason: COS-1 experiments report reduced enzyme activity for disease variants, including variants that reach lysosomes. Activity loss and altered trafficking are separable observations; abnormal ER retention is not a normal core location. Supporting Evidence: PMID:19472408 significantly reduced beta-Gal activities (<10% of normal) upon expression in COS-1 cells. |
| GO:0004565 beta-galactosidase activity | IDA PMID:24737316 Structural basis of pharmacological chaperoning for human Ξ²-... | ACCEPT | Summary: Purified human enzyme measurements support beta-galactosidase activity. Reason: Wild-type and mutant enzyme inhibition studies directly assess this catalytic function. Pharmacological chaperoning of GLB1 does not establish an endogenous chaperone activity for the enzyme. Supporting Evidence: PMID:24737316 enzymological properties of purified recombinant human Ξ²-Gal |
| GO:0004565 beta-galactosidase activity | EXP PMID:2511208 Alternative splicing of beta-galactosidase mRNA generates th... | ACCEPT | Summary: The long GLB1 product has beta-galactosidase activity. Reason: The cDNA study distinguishes an active long product from a shorter product lacking activity under the tested conditions. Preserve the entry-level annotation with that product boundary. Supporting Evidence: PMID:2511208 Only the long protein is catalytically active under the assay conditions used |
| GO:0004565 beta-galactosidase activity | IMP PMID:25936995 Recurrent and novel GLB1 mutations in India. | ACCEPT | Summary: The human deficiency study is consistent with GLB1 catalytic activity. Reason: The accessible clinical report concerns GLB1-associated enzyme deficiency. Retain the curator's IMP assignment for this independently established function; do not represent the mutation survey or its computational analyses as a purified-enzyme experiment. |
| GO:0004565 beta-galactosidase activity | TAS PMID:3143362 Cloning, sequencing, and expression of cDNA for human beta-g... | ACCEPT | Summary: Expression of human GLB1 cDNA increases beta-galactosidase activity. Reason: The reported cDNA encodes the 677-residue precursor and supports the active enzyme. The assay establishes catalytic activity for the long product. Supporting Evidence: PMID:3143362 led to an increase in beta-galactosidase activity |
| GO:0004565 beta-galactosidase activity | TAS PMID:3143362 Cloning, sequencing, and expression of cDNA for human beta-g... | ACCEPT | Summary: The human cDNA defines an active beta-galactosidase precursor. Reason: Expression increases beta-galactosidase activity, supporting the normal long product. This evidence does not assign catalysis to the shorter elastin-binding product. |
| GO:0004565 beta-galactosidase activity | IMP PMID:8112731 Intracellular processing and maturation of mutant gene produ... | ACCEPT | Summary: Human variant processing experiments support beta-galactosidase activity. Reason: Morquio B and other GLB1 variants show altered activity or stability. The protective protein's role in stabilizing GLB1 must not be confused with which product catalyses galactoside hydrolysis. Supporting Evidence: PMID:8112731 transported to lysosomes, but its catalytic activity was low |
| GO:0004565 beta-galactosidase activity | EXP PMID:8200356 Hydrolysis of lactosylceramide by human galactosylceramidase... | ACCEPT | Summary: Purified human GLB1 hydrolyses beta-galactoside substrates. Reason: The study compares GLB1 and GALC with saposin-dependent lipid substrates. It supports GLB1 catalysis, including lactosylceramide under the stated assay conditions, without transferring GALC specificity or asserting every in vitro substrate is a principal physiological substrate. Supporting Evidence: PMID:8200356 sap-B was a better activator for the reaction catalyzed by GM1-beta-galactosidase |
| GO:0004565 beta-galactosidase activity | TAS Reactome:R-HSA-2265534 | ACCEPT | Summary: The normal GLB1 product has beta-galactosidase activity. Reason: This cited event models inactive disease variants. Its explicit normal counterpart, R-HSA-1630306, places GLB1 in the beta-galactosidase catalyst. Retain the normal-product activity without claiming that the modeled mutants perform the failed reaction. Supporting Evidence: Reactome:R-HSA-2265534 Reactome:R-HSA-1630306 |
| GO:0004565 beta-galactosidase activity | TAS Reactome:R-HSA-9036061 | ACCEPT | Summary: GLB1 catalyses terminal beta-galactoside hydrolysis. Reason: The cited disease event has no products; its normalReaction link is R-HSA-2090079. That normal reaction supplies the positive catalytic context. Mutant loss and normal enzymatic activity must remain separate statements. Supporting Evidence: Reactome:R-HSA-9036061 Reactome:R-HSA-2090079 |
| GO:0005515 protein binding | IPI PMID:15498789 Role of a novel EGF-like domain-containing gene NGX6 in cell... | UNDECIDED | Summary: The cited interaction has an unresolved citation-target concern. Reason: The recovered original tests NGX6 from accession AF188239 with ezrin. That construct is distinct from the GLB1 products. This warrants checking the historical interaction record; an empty current IntAct response neither identifies an error mechanism nor excludes a GLB1-ezrin interaction. Keep the experimental annotation unresolved instead of asserting misattribution. |
| GO:0005515 protein binding | IPI PMID:22128166 Crystal structure of human Ξ²-galactosidase: structural basis... | MODIFY | Summary: The observed association is specifically homodimerization. Reason: Crystal and solution measurements support a recombinant-enzyme dimer. Use the specific term already represented by the homodimerization annotation, without asserting universal physiological stoichiometry. Proposed replacements: protein homodimerization activity |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | REMOVE | Summary: HuRI detects a GLB1-SLC7A1 assay interaction. Reason: Yeast two-hybrid support is present. Remove generic binding for lack of functional information, without rejecting the interaction or assigning transport activity. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | REMOVE | Summary: HuRI detects a GLB1-SLC10A6 assay interaction. Reason: The paired yeast two-hybrid records are verified. Generic binding adds no specific GLB1 function or physiological-complex assignment. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | REMOVE | Summary: HuRI detects a GLB1-GOLM1 assay interaction. Reason: The tested GOLM1 region is 2-401. Remove uninformative binding without inferring a Golgi role or the assayed GLB1 isoform. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | REMOVE | Summary: HuRI detects a GLB1-SLC30A2 assay interaction. Reason: Verified yeast two-hybrid support does not identify a GLB1 molecular role. Removing generic binding does not reject the interaction. |
| GO:0016787 hydrolase activity | IEA GO_REF:0000107 | TOO GENERAL | Summary: The active GLB1 product has a specifically identified hydrolytic activity. Reason: Accepted GO:0004565 beta-galactosidase activity is a descendant of hydrolase activity. This broad term adds no distinct function. |
| GO:0016936 galactoside binding | IEA GO_REF:0000107 | UNDECIDED | Summary: The galactoside-binding transfer traces to an experimental rat annotation whose assay remains unresolved. Reason: The donor D3ZUM4 is verified rat Glb1, and its IDA source is PMID:8702598. The accessible abstract concerns lysosomal enzymes and mannose-6-phosphate-dependent affinity; it does not resolve this binding annotation. The full original remained inaccessible. Do not infer a misattribution or a distinct human binding function from this incomplete record. |
| GO:0042803 protein homodimerization activity | IPI PMID:22128166 Crystal structure of human Ξ²-galactosidase: structural basis... | KEEP AS NON CORE | Summary: Processed recombinant human GLB1 forms a dimer in the studied preparation. Reason: Retain this structural property as secondary to catalysis. The original authors leave physiological oligomerization unresolved; alternate products and all mature complexes are not thereby shown to be dimeric. |
| GO:0005975 carbohydrate metabolic process | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Retain the broad carbohydrate-metabolic assignment as a secondary process context. Reason: The substrate-specific catabolic processes already retained elsewhere do not entail GO:0005975 in the checked ontology. Replacing this claim with those lateral terms would lose the broad assignment. Keep it consistently with the experimental row; the available evidence does not justify a more specific descendant. |
| GO:0005975 carbohydrate metabolic process | IDA PMID:11927518 Endothelial cell senescence in human atherosclerosis: role o... | KEEP AS NON CORE | Summary: The endothelial staining supports a broad carbohydrate-metabolic context. Reason: Retain the curator's process assignment with its joint aortic-endothelial-cell and cytoplasm extension. The accessible staining report does not identify a specific endogenous glycan substrate, so it cannot alone justify a more specific replacement or a senescence-driving role. |
| GO:0006516 glycoprotein catabolic process | IEA GO_REF:0000107 | ACCEPT | Summary: GLB1 degrades glycoprotein-derived glycans. Reason: Terminal-galactose hydrolysis directly contributes to their degradation; human evidence corroborates the orthology transfer. |
| GO:0006516 glycoprotein catabolic process | IMP PMID:31720227 Characterization of glycan substrates accumulating in GM1 Ga... | ACCEPT | Summary: Human deficiency supports glycoprotein catabolism. Reason: Patient glycan accumulation agrees with recombinant-enzyme removal of terminal galactose. Retain the original IMP evidence. Supporting Evidence: |
| GO:0006689 ganglioside catabolic process | IEA GO_REF:0000120 | ACCEPT | Summary: The active lysosomal product degrades gangliosides. Reason: Human biochemistry and substrate accumulation corroborate the electronic assignment; the inactive splice product is excluded. |
| GO:0006689 ganglioside catabolic process | IMP PMID:31720227 Characterization of glycan substrates accumulating in GM1 Ga... | ACCEPT | Summary: GLB1 participates in ganglioside catabolism. Reason: GM1/GA1 accumulate in affected human brain, consistent with the established catalytic step. Supporting Evidence: PMID:31720227 leads to the lysosomal accumulation of GM1 and its asialo derivative GA1 |
| GO:0019388 galactose catabolic process | IBA GO_REF:0000033 | UNDECIDED | Summary: The galactose-catabolic IBA has a verified ancestral placement but an unresolved substrate-process interpretation. Reason: The actual assertion at AN0/PTN000602923 includes the human target within its descendants and has experimental rat grounding in PMID:6811372. Current GO:0019388 describes breakdown of galactose, whereas GLB1 hydrolysis releases galactose from glycoconjugates. The donor's full experiment was unavailable, so the chemistry distinction motivates uncertainty without alleging a curator error or circularity. Propagation Review Root cause: UNRESOLVED Sources checked: PANTHER:PTN000602923 Β· PTN000602923 UNRESOLVED AN0 placement and human descent are verified; the exact process interpretation remains unresolved. RGD:1597145 Β· Glb1 UNRESOLVED IDA source PMID:6811372 is verified; its complete experiment remains unavailable. |
| GO:0019388 galactose catabolic process | IEA GO_REF:0000107 | UNDECIDED | Summary: The rat-to-human galactose-catabolic transfer requires the same unresolved process interpretation. Reason: D3ZUM4 carries an IDA annotation from PMID:6811372, but the full original was not recovered. The abstract establishes acid beta-galactosidase variation and activity, without resolving the current term's distinction between galactose breakdown and glycoside hydrolysis. Preserve the original experimental provenance and do not reject it from abstract omission. |
| GO:0042340 keratan sulfate proteoglycan catabolic process | IEA GO_REF:0000120 | ACCEPT | Summary: GLB1 contributes to keratan sulfate degradation. Reason: Terminal-galactose hydrolysis and human deficiency support the electronic process assignment for the active product. |
| GO:0042340 keratan sulfate proteoglycan catabolic process | IMP PMID:31720227 Characterization of glycan substrates accumulating in GM1 Ga... | ACCEPT | Summary: Patient measurements support keratan sulfate catabolism. Reason: Three of six affected patients exceeded the normal urinary reference. This is IMP evidence, not a purified-enzyme cleavage assay. Supporting Evidence: |
| GO:0051413 response to cortisone | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: A developmental enzyme-activity response to cortisone is transferred from rat. Reason: The donor's IEP source explicitly reports cortisone-dependent changes in developing intestinal acid beta-galactosidase activity. Retain this contextual response as non-core, with abstract-only access and the cross-species inference explicit. It does not imply cortisone binding, receptor activity or hormone catabolism by GLB1. Supporting Evidence: PMID:6411136 a single injection of cortisone acetate on day 6 caused a precocious reduction of the activities of both enzymes |
| GO:1904016 response to Thyroglobulin triiodothyronine | IEA GO_REF:0000107 | UNDECIDED | Summary: The rat T3-response experiment leaves the precise current stimulus term unresolved. Reason: The donor IEP source reports altered fetal intestinal enzyme activity after maternal T3 administration. Current GO:1904016 refers to a thyroglobulin-bound triiodothyronine group, CHEBI:80690, which differs from free T3. Keep the observation but leave this exact transfer unresolved; the full donor experiment was unavailable. Do not infer hormone binding, metabolism or a particular curation-error mechanism. |
| GO:0005764 lysosome | IBA GO_REF:0000033 | ACCEPT | Summary: Lysosomal localization is an inherited property of the canonical vertebrate enzyme. Reason: The actual lysosome assertion is at AN146/PTN002765259, within the vertebrate lineage and ancestral to human AN156. It agrees with direct human enzyme processing and localization evidence. The deeper catalytic assertion and the plant branch are distinct from this location assertion; entry-level inheritance does not demonstrate lysosomal localization of the elastin-binding product. |
| GO:0005764 lysosome | IMP PMID:8112731 Intracellular processing and maturation of mutant gene produ... | ACCEPT | Summary: The active GLB1 product is a lysosomal enzyme. Reason: The human variant-processing study distinguishes lysosomal delivery from loss of activity and rapid degradation. Those mutant outcomes support analysis of the normal lysosomal product without placing every alternate product there. |
| GO:0005576 extracellular region | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Extracellular occurrence is compatible with specific GLB1 release contexts. Reason: The transferred location is corroborated by human Reactome cargo models and urinary-vesicle evidence. Preserve it as a secondary location; it does not establish extracellular hydrolysis as the main role or active participation in secretion machinery. |
| GO:0005576 extracellular region | TAS Reactome:R-HSA-6798751 | KEEP AS NON CORE | Summary: GLB1 is modeled as released azurophil-granule cargo. Reason: The event output set contains the exact P16278 extracellular entity. Retain this location while keeping lysosomal hydrolysis central; being released cargo does not mean GLB1 performs exocytosis. Supporting Evidence: Reactome:R-HSA-6798751 |
| GO:0005576 extracellular region | TAS Reactome:R-HSA-6800434 | KEEP AS NON CORE | Summary: GLB1 can occur extracellularly after granule release. Reason: The ficolin-rich granule event places the P16278 entity in its extracellular output set. This supports the location, not a new secretion-machinery or signaling function. Supporting Evidence: Reactome:R-HSA-6800434 |
| GO:0005737 cytoplasm | IEA GO_REF:0000107 | TOO GENERAL | Summary: Product-specific locations provide the relevant cytoplasmic resolution. Reason: The unqualified electronic cytoplasm annotation is entailed by the retained lysosomal-lumen and perinuclear-cytoplasm assignments. Both are actual descendants. Cytoplasm includes organelles, so this is not a claim that the source incorrectly placed a lysosomal enzyme in cytosol. |
| GO:0005737 cytoplasm | IDA PMID:11927518 Endothelial cell senescence in human atherosclerosis: role o... | TOO GENERAL | Summary: The broad cytoplasm term is subsumed by retained, more specific locations. Reason: The retained lysosomal-lumen and perinuclear-cytoplasm assignments entail cytoplasm. The coronary-artery and endothelial-cell extensions preserve the experimental context but do not refine this subcellular term. Keep both extension atoms unchanged; this decision neither relocates the staining to an independently resolved organelle nor calls the original observation false. |
| GO:0005764 lysosome | IEA GO_REF:0000120 | ACCEPT | Summary: The lysosome mapping identifies the active GLB1 product's main compartment. Reason: UniProt explicitly assigns SL-0158 to isoform 1, supported by human cDNA and localization studies. Preserve the entry-level source while keeping the isoform boundary explicit. |
| GO:0005764 lysosome | EXP PMID:2511208 Alternative splicing of beta-galactosidase mRNA generates th... | ACCEPT | Summary: The long cDNA product is the lysosomal enzyme. Reason: The source distinguishes active and shorter inactive products with different subcellular localizations. UniProt's isoform-resolved location record links the lysosomal assignment to the long product and this publication. |
| GO:0005764 lysosome | EXP PMID:3084261 Immunoelectron microscopical localization of lysosomal beta-... | ACCEPT | Summary: The mature enzyme localizes to lysosomes in human fibroblasts. Reason: The immunoelectron-microscopy study places mature enzyme in lysosomal multimers. Precursor trafficking and abnormal mutant surface localization do not alter this normal mature-enzyme assignment. Supporting Evidence: PMID:3084261 In the lysosomes virtually all beta-gal exists as a high molecular weight multimer of mature enzyme. |
| GO:0035578 azurophil granule lumen | TAS Reactome:R-HSA-6798751 | KEEP AS NON CORE | Summary: GLB1 is present in the azurophil-granule lumen. Reason: The input set explicitly contains human P16278 in this compartment. This specialized granule pool is distinct from the principal lysosomal catalytic setting. Supporting Evidence: Reactome:R-HSA-6798751 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-1605624 | ACCEPT | Summary: The beta-galactosidase catalyst occupies the lysosomal lumen. Reason: The normal reaction identifies BGAL, whose confirmed member is the GLB1 dimer. The dimer component resolves to P16278 in the lumen. The event also lists a membrane compartment for other participants; that does not place GLB1 in the membrane. Supporting Evidence: Reactome:R-HSA-1605624 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-1605724 | ACCEPT | Summary: GLB1 is a luminal component of a lysosomal enzyme complex. Reason: The NEU1,4 catalyst set includes the NEU1:GLB1:CTSA complex and its P16278 component. This supports the location; the sialidase chemistry belongs to NEU1, not to GLB1. Supporting Evidence: Reactome:R-HSA-1605724 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-1606312 | ACCEPT | Summary: GLB1 acts in the lysosomal lumen during lactosylceramide hydrolysis. Reason: The BGAL catalyst contains the GLB1 dimer in this compartment. The substrate context supports luminal catalysis without changing the protein identity. Supporting Evidence: Reactome:R-HSA-1606312 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-1630306 | ACCEPT | Summary: GLB1-mediated glycosaminoglycan hydrolysis occurs in the lysosomal lumen. Reason: The normal reaction connects its catalyst through BGAL to the GLB1 dimer and P16278. Retain the directly modeled catalytic compartment. Supporting Evidence: Reactome:R-HSA-1630306 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-2090079 | ACCEPT | Summary: GLB1 cleaves linker-chain galactose residues in the lysosomal lumen. Reason: The normal linker-chain reaction identifies the same luminal GLB1 catalyst. This is an enzyme role rather than mere presence of a nearby substrate. Supporting Evidence: Reactome:R-HSA-2090079 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-2265534 | ACCEPT | Summary: The lysosomal-lumen assignment is supported for GLB1. Reason: The cited reaction concerns defective GLB1 variants; the normal counterpart R-HSA-1630306 independently places the normal catalyst in this lumen. Do not infer residual mutant activity from the compartment assignment. Supporting Evidence: Reactome:R-HSA-2265534 Reactome:R-HSA-1630306 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-4084999 | ACCEPT | Summary: GLB1 occupies the lysosomal lumen within the NEU1-containing complex. Reason: The catalyst complex contains P16278 in this compartment. Retain the location while distinguishing GLB1 from the NEU1 subunit performing sialic-acid cleavage. Supporting Evidence: Reactome:R-HSA-4084999 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-4341669 | ACCEPT | Summary: GLB1 remains a luminal component in the NEU1 disease model. Reason: Here the altered subunit is NEU1. The modeled complex still contains the ordinary P16278 GLB1 component in the lysosomal lumen; no GLB1 sialidase activity is implied. Supporting Evidence: Reactome:R-HSA-4341669 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-9036061 | ACCEPT | Summary: The linker-chain models place GLB1 in the lysosomal lumen. Reason: The cited disease reaction concerns GLB1 variants. Its normal counterpart R-HSA-2090079 independently supplies the normal-product compartment, so location is retained without treating the failed reaction as positive catalysis. Supporting Evidence: Reactome:R-HSA-9036061 Reactome:R-HSA-2090079 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-9638120 | ACCEPT | Summary: GLB1 is a luminal component of the modeled NEU4-containing complex. Reason: The NEU4:GLB1:CTSA complex explicitly contains P16278 in the lumen. This is a compartment assertion and does not transfer NEU4 catalytic specificity to GLB1. Supporting Evidence: Reactome:R-HSA-9638120 |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-9840795 | ACCEPT | Summary: GLB1 catalysis in the GA1 reaction is assigned to the lysosomal lumen. Reason: The BGAL catalyst has the GLB1 dimer as its confirmed member. The exact P16278 component and compartment support this existing location independently of the GM2A-bound substrate. Supporting Evidence: Reactome:R-HSA-9840795 |
| GO:0048471 perinuclear region of cytoplasm | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Perinuclear cytoplasmic localization concerns the shorter GLB1 product. Reason: The actual UniProt SL-0198 comment belongs to isoform 2 and cites PMID:2511208. Preserve the unsuffixed incoming annotation, but do not apply this localization to the active lysosomal product or fabricate an isoform identifier in the machine context. Supporting Evidence: file:human/GLB1/GLB1-uniprot.txt Localized to the perinuclear area of the cytoplasm but not to lysosomes. |
| GO:0070062 extracellular exosome | HDA PMID:19056867 Large-scale proteomics and phosphoproteomics of urinary exos... | KEEP AS NON CORE | Summary: GLB1 was detected in human urinary exosome preparations. Reason: The original authors' database identifies GLB1/NP_000395 and explicitly links this study. Preserve the urine extension and high-throughput localization as a secondary observation. Detection does not establish exosome formation, transport machinery or extracellular catalytic function. |
| GO:0070062 extracellular exosome | HDA PMID:23533145 In-depth proteomic analyses of exosomes isolated from expres... | KEEP AS NON CORE | Summary: GLB1 is detected in pooled EPS-urine exosome preparations. Reason: Original Supplemental Table 2 identifies P16278/GLB1 in both pooled groups and technical duplicates. Preserve the HDA localization as secondary. Co-isolation and pooling preclude an isoform-specific, cancer-specific or exosome-biogenesis interpretation. |
| GO:1904813 ficolin-1-rich granule lumen | TAS Reactome:R-HSA-6800434 | KEEP AS NON CORE | Summary: GLB1 is modeled in ficolin-1-rich granule lumen. Reason: The event input set contains the exact P16278 entity in this compartment. Preserve the specialized cargo location without adding an exocytosis process assertion. Supporting Evidence: Reactome:R-HSA-6800434 |
| GO:0050840 extracellular matrix binding | IDA P16278-2 PMID:9497360 The 67-kDa enzymatically inactive alternatively spliced vari... | NEW | Summary: The human S-Gal splice product binds extracellular-matrix ligands. Reason: Human S-Gal expression supports elastin retention and laminin recovery with collagen controls. Restrict matrix binding to the shorter product; neither enzymatic elastin degradation nor a purified two-component affinity constant is established. Supporting Evidence: PMID:9497360 bound to elastin and laminin affinity columns file:human/GLB1/GLB1-deep-research-manual.md |
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Download this section (compressed HTML)Q: Which GLB1-containing oligomeric assemblies predominate in human lysosomes at physiological pH, and how do they differ from the processed recombinant dimer?
Q: Which steps of tropoelastin secretion and elastic-fiber assembly require direct S-Gal binding, and which depend on other components of the elastin-receptor system?
Q: What distinguishes the localization and catalytic capacity of the 647-residue P16278-3 product from the established long and S-Gal products?
Experiment: Measure endogenous lysosomal GLB1 stoichiometry and partners with native separation and orthogonal structural or cross-linking measurements across controlled luminal pH conditions.
Experiment: Compare isoform-specific S-Gal rescue with ligand-binding-defective constructs while tracking tropoelastin secretion and matrix incorporation, separating ligand association from downstream receptor effects.
Experiment: Express sequence-verified P16278-3 alongside P16278-1 and P16278-2 under matched conditions and measure processing, localization and substrate-specific catalysis.
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