NAGLU

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0004561 alpha-N-acetylglucosaminidase activity	IBA GO_REF:0000033	ACCEPT	Summary: Phylogenetic (IBA) assignment of the core catalytic molecular function of NAGLU, alpha-N-acetylglucosaminidase activity, propagated across the GH89 family from experimentally characterized orthologs. Reason: This is the defining, experimentally established activity of NAGLU: hydrolysis of terminal non-reducing N-acetyl-D-glucosamine residues in N-acetyl-alpha-D-glucosaminides (EC 3.2.1.50), consistent with the GO term definition and UniProt. The IBA assignment is correct and at the right level of specificity; retained as a core function. Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt Reaction=Hydrolysis of terminal non-reducing N-acetyl-D-glucosamine residues in N-acetyl-alpha-D-glucosaminides.; EC=3.2.1.50 PMID:8650226 The Sanfilippo syndrome type B is a lysosomal storage disorder caused by deficiency of alpha-N-acetylglucosaminidase
GO:0005773 vacuole	IBA GO_REF:0000033	ACCEPT	Summary: Phylogenetic (IBA) location annotation to vacuole, the lineage-general parent of the lysosome used by GO_Central for this family. Reason: Vacuole (GO:0005773) is the broad, taxon-general term encompassing the lysosome, where NAGLU actually acts in animals. It is correct but less specific than the lysosome/lysosomal lumen annotations also present; accepted as a valid (if general) location. The specific human location is captured by the lysosome and lysosomal lumen annotations. Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt SUBCELLULAR LOCATION: Lysosome.
GO:0030202 heparin proteoglycan metabolic process	IBA GO_REF:0000033	MODIFY	Summary: Phylogenetic (IBA) biological-process annotation placing NAGLU in heparin proteoglycan metabolism. Reason: Heparin is a highly sulfated variant of heparan sulfate and NAGLU acts on the shared alpha-N-acetylglucosamine linkage, so the annotation is not wrong; however the primary, disease-relevant process for NAGLU is the lysosomal catabolism of heparan sulfate. Modify to the more accurate and specific heparan sulfate proteoglycan catabolic process, which is what the enzyme's deficiency (MPS IIIB) directly impairs. Proposed replacements: heparan sulfate proteoglycan catabolic process Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt FUNCTION: Involved in the degradation of heparan sulfate. Reactome:R-HSA-1678742 Alpha-N-acetylglucosaminidase (NAGLU) hydrolyses the non-reducing, terminal N-acetyl-D-glucosamine residue from heparan sulfate.
GO:0004561 alpha-N-acetylglucosaminidase activity	IEA GO_REF:0000003	ACCEPT	Summary: Electronic (IEA) annotation of alpha-N-acetylglucosaminidase activity derived from the EC 3.2.1.50 to GO mapping. Reason: The EC-to-GO mapping is exactly correct: NAGLU carries EC 3.2.1.50, and the reaction matches the GO term definition. Accepted as a redundant but valid statement of the core molecular function. Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt RecName: Full=Alpha-N-acetylglucosaminidase; DE EC=3.2.1.50;
GO:0005764 lysosome	IEA GO_REF:0000044	ACCEPT	Summary: Electronic (IEA) location annotation to lysosome from the UniProt subcellular-location keyword mapping. Reason: NAGLU is a soluble lysosomal hydrolase; the lysosome is its established site of action. Correct and core; consistent with the experimental (TAS) lysosome annotation from PMID:8650226. Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt SUBCELLULAR LOCATION: Lysosome.
GO:0048731 system development	IEA GO_REF:0000117	MARK AS OVER ANNOTATED	Summary: ARBA machine-learning (IEA) biological-process annotation to the very general term system development. Reason: This general developmental term reflects the disease phenotype (multi-system, predominantly neurological deterioration in MPS IIIB) rather than a direct developmental role of the enzyme. The observed developmental defects are downstream consequences of impaired heparan sulfate catabolism and lysosomal storage, not a molecular developmental function of NAGLU. Uninformative at this level and over-annotated. Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt MPS3 is characterized by severe central nervous system degeneration, but only mild somatic disease.
GO:1901135 carbohydrate derivative metabolic process	IEA GO_REF:0000117	MODIFY	Summary: ARBA machine-learning (IEA) biological-process annotation to the general term carbohydrate derivative metabolic process. Reason: NAGLU does act in the metabolism of a carbohydrate derivative (heparan sulfate, an N-acetylglucosamine-containing glycosaminoglycan), so the term is not incorrect, but it is far too general to be informative. Modify to the specific heparan sulfate proteoglycan catabolic process that captures the actual biology. Proposed replacements: heparan sulfate proteoglycan catabolic process Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt FUNCTION: Involved in the degradation of heparan sulfate.
GO:0030200 heparan sulfate proteoglycan catabolic process	TAS Reactome:R-HSA-2024096	ACCEPT	Summary: Reactome (TAS) annotation placing NAGLU in the lysosomal degradation of heparan sulfate glycosaminoglycan (HS-GAG degradation pathway). Reason: This is the core biological process for NAGLU. The enzyme performs one exolytic step in the ordered lysosomal breakdown of heparan sulfate, removing terminal alpha-N-acetylglucosamine residues; its deficiency blocks this catabolic pathway and causes MPS IIIB. Accepted as a core function and used as the preferred replacement for the more general/heparin-specific process annotations. Supporting Evidence: Reactome:R-HSA-2024096 The steps outlined below describe the cleavage of heparan sulfate/heparin from heparan sulfate proteoglycans (HSPGs) and its degradation. file:human/NAGLU/NAGLU-uniprot.txt FUNCTION: Involved in the degradation of heparan sulfate.
GO:0004561 alpha-N-acetylglucosaminidase activity	TAS Reactome:R-HSA-1678742	ACCEPT	Summary: Reactome (TAS) annotation of the core catalytic activity in the reaction "NAGLU hydrolyses Heparan sulfate chain(4)". Reason: Directly supported: Reactome describes NAGLU hydrolysing the non-reducing terminal N-acetyl-D-glucosamine residue from heparan sulfate, which is exactly alpha-N-acetylglucosaminidase activity. Redundant with the IBA/IEA MF annotations but valid; core function. Supporting Evidence: Reactome:R-HSA-1678742 Alpha-N-acetylglucosaminidase (NAGLU) hydrolyses the non-reducing, terminal N-acetyl-D-glucosamine residue from heparan sulfate.
GO:0004561 alpha-N-acetylglucosaminidase activity	TAS Reactome:R-HSA-2090038	ACCEPT	Summary: Reactome (TAS) annotation of the core catalytic activity in a second heparan chain hydrolysis reaction. Reason: Same well-supported core molecular function as the other alpha-N-acetylglucosaminidase activity annotations, from a distinct Reactome reaction. Redundant but valid. Supporting Evidence: Reactome:R-HSA-1678742 Alpha-N-acetylglucosaminidase (NAGLU) hydrolyses the non-reducing, terminal N-acetyl-D-glucosamine residue from heparan sulfate.
GO:0004561 alpha-N-acetylglucosaminidase activity	TAS Reactome:R-HSA-2263496	ACCEPT	Summary: Reactome (TAS) annotation of the core catalytic activity, from a reaction contrasting wild-type with defective NAGLU. Reason: Restates the core alpha-N-acetylglucosaminidase activity of NAGLU. Redundant with the other MF annotations but valid and correctly attributed. Supporting Evidence: Reactome:R-HSA-1678742 Alpha-N-acetylglucosaminidase (NAGLU) hydrolyses the non-reducing, terminal N-acetyl-D-glucosamine residue from heparan sulfate.
GO:0004561 alpha-N-acetylglucosaminidase activity	TAS Reactome:R-HSA-9036052	ACCEPT	Summary: Reactome (TAS) annotation of the core catalytic activity, from a further heparan chain hydrolysis reaction. Reason: Restates the core alpha-N-acetylglucosaminidase activity. Redundant with the other MF annotations but valid. Supporting Evidence: Reactome:R-HSA-1678742 Alpha-N-acetylglucosaminidase (NAGLU) hydrolyses the non-reducing, terminal N-acetyl-D-glucosamine residue from heparan sulfate.
GO:0043202 lysosomal lumen	TAS Reactome:R-HSA-2263496	ACCEPT	Summary: Reactome (TAS) location annotation placing NAGLU in the lysosomal lumen, where it acts on soluble heparan sulfate fragments. Reason: NAGLU is a soluble lysosomal hydrolase acting in the lysosomal lumen; this is the precise compartment for its activity and is core. Consistent with the lysosome annotations. Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt SUBCELLULAR LOCATION: Lysosome.
GO:0043202 lysosomal lumen	TAS Reactome:R-HSA-9036052	ACCEPT	Summary: Reactome (TAS) location annotation to lysosomal lumen, from a second reaction. Reason: Same well-supported core lysosomal-lumen location as the other lysosomal lumen annotation. Redundant but valid. Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt SUBCELLULAR LOCATION: Lysosome.
GO:0070062 extracellular exosome	HDA PMID:23533145 In-depth proteomic analyses of exosomes isolated from expres...	KEEP AS NON CORE	Summary: High-throughput mass-spectrometry (HDA) detection of NAGLU in exosomes isolated from expressed prostatic secretions in urine. Reason: NAGLU was identified in a bulk shotgun-proteomics survey of urinary/prostatic exosomes. Presence of lysosomal enzymes in secreted extracellular vesicles is a real but peripheral observation and does not reflect the core lysosomal catabolic function of the enzyme. Retained as a non-core localization. Supporting Evidence: PMID:23533145 exosome preparations were characterized by a shotgun proteomics procedure. In pooled EPS-urine exosome samples, ~900 proteins were detected.
GO:0070062 extracellular exosome	IDA PMID:21082674 Comprehensive analysis of low-abundance proteins in human ur...	KEEP AS NON CORE	Summary: Proteomic (IDA) detection of NAGLU among low-abundance proteins in human urinary exosomes. Reason: NAGLU was detected in a targeted low-abundance urinary-exosome proteome. As with the other exosome annotations, this is a peripheral localization observation, not the core lysosomal function; retained as non-core. Supporting Evidence: PMID:21082674 After analysis by nanoHPLC-chip-MS/MS, 512 proteins were identified
GO:0070062 extracellular exosome	HDA PMID:19056867 Large-scale proteomics and phosphoproteomics of urinary exos...	KEEP AS NON CORE	Summary: Large-scale mass-spectrometry (HDA) detection of NAGLU in the human urinary exosome proteome. Reason: NAGLU was among the ~1132 proteins profiled in urinary exosomes by LC-MS/MS. Consistent with the other exosome detections; a real but non-core localization for a lysosomal hydrolase. Supporting Evidence: PMID:19056867 the analysis identified 1132 proteins unambiguously
GO:0043202 lysosomal lumen	TAS Reactome:R-HSA-1678742	ACCEPT	Summary: Reactome (TAS) location annotation to lysosomal lumen, from the primary NAGLU heparan sulfate hydrolysis reaction. Reason: Correct core compartment for NAGLU's soluble hydrolase activity, tied directly to the reaction in which it degrades heparan sulfate. Consistent with other lysosomal annotations. Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt SUBCELLULAR LOCATION: Lysosome.
GO:0043202 lysosomal lumen	TAS Reactome:R-HSA-2090038	ACCEPT	Summary: Reactome (TAS) location annotation to lysosomal lumen, from a second heparan hydrolysis reaction. Reason: Same well-supported core lysosomal-lumen location. Redundant but valid. Supporting Evidence: file:human/NAGLU/NAGLU-uniprot.txt SUBCELLULAR LOCATION: Lysosome.
GO:0004561 alpha-N-acetylglucosaminidase activity	TAS PMID:8650226 The molecular basis of Sanfilippo syndrome type B.	ACCEPT	Summary: Author-statement (TAS) annotation of alpha-N-acetylglucosaminidase activity from the foundational paper that cloned NAGLU and defined Sanfilippo B as its deficiency. Reason: This is the primary literature establishing NAGLU as alpha-N-acetylglucosaminidase: the cDNA/gene was cloned starting from purified enzyme, and the disease is defined by deficiency of this activity. Core molecular function, strongly supported. Supporting Evidence: PMID:8650226 The Sanfilippo syndrome type B is a lysosomal storage disorder caused by deficiency of alpha-N-acetylglucosaminidase
GO:0005764 lysosome	TAS PMID:8650226 The molecular basis of Sanfilippo syndrome type B.	ACCEPT	Summary: Author-statement (TAS) annotation of lysosomal localization from the foundational NAGLU cloning paper. Reason: NAGLU is characterized as a lysosomal enzyme whose deficiency causes a lysosomal storage disorder; the lysosome is its established site of action. Core location, experimentally grounded. Supporting Evidence: PMID:8650226 The Sanfilippo syndrome type B is a lysosomal storage disorder caused by deficiency of alpha-N-acetylglucosaminidase
GO:0007399 nervous system development	TAS PMID:8650226 The molecular basis of Sanfilippo syndrome type B.	MARK AS OVER ANNOTATED	Summary: Author-statement (TAS) annotation to nervous system development, reflecting the profound neurological phenotype of NAGLU deficiency (Sanfilippo B). Reason: The neurological phenotype of MPS IIIB (profound mental deterioration, CNS degeneration) is a downstream pathological consequence of failed lysosomal heparan sulfate catabolism and progressive storage, not a direct developmental function of the enzyme. NAGLU is a housekeeping lysosomal glycosidase; annotating it to nervous system development conflates disease phenotype with molecular role and over-annotates. The core biology is captured by the catabolic-process and lysosome annotations. Supporting Evidence: PMID:8650226 it is characterized by profound mental deterioration in childhood and death in the second decade

Gene Description

Existing Annotations Review

Core Functions

Lysosomal alpha-N-acetylglucosaminidase that hydrolyses terminal non-reducing alpha-N-acetyl-D-glucosamine residues in heparan sulfate, carrying out one exolytic step in the stepwise lysosomal catabolism of heparan sulfate glycosaminoglycan.

References

📚 Additional Documentation

Notes

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