ARSA (arylsulfatase A, also called cerebroside-sulfatase or cerebroside-3-sulfatase; EC 3.1.6.8) is a lysosomal sulfatase of the glycosphingolipid degradation pathway. It hydrolytically removes the 3-O-sulfate from sulfatide (3-O-sulfogalactosylceramide, cerebroside-3-sulfate) to give galactosylceramide (cerebroside) plus sulfate, and also desulfates other sulfated glycolipids such as seminolipid and lactosylceramide sulfate (SM3). Catalysis requires the lipid-presenting activator protein saposin B (a cleavage product of PSAP) and a catalytic Calpha-formylglycine residue at Cys69 that is generated post-translationally in the endoplasmic reticulum by the formylglycine-generating enzyme SUMF1; a Ca2+ ion is bound in the active site. The enzyme is synthesized and matured in the ER and delivered to the lysosomal lumen via the mannose-6-phosphate receptor pathway, where it acts at acidic pH. Loss of ARSA activity causes intralysosomal accumulation of sulfatide and the demyelinating lysosomal storage disorder metachromatic leukodystrophy (MLD).
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004065 arylsulfatase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Family-level molecular function inferred phylogenetically across the arylsulfatase clade. ARSA is a bona fide arylsulfatase that hydrolyzes aryl sulfate esters (used as surrogate diagnostic substrates) and, physiologically, the natural sulfatide substrate. This is a correct broad MF; the more specific cerebroside-sulfatase term captures the physiological reaction. Reason: IBA is well-reviewed and correctly places ARSA in the arylsulfatase family. Retained as the broader family MF; the specific physiological MF is GO:0004098. Supporting Evidence: PMID:2562955 Transfection of monkey and baby hamster kidney cells resulted in an up to 200-fold increase of the arylsulfatase A activity. |
| GO:0004098 cerebroside-sulfatase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Specific molecular function: hydrolysis of the 3-O-sulfate of sulfatide (cerebroside-3-sulfate) to give cerebroside (galactosylceramide) and sulfate (RHEA:21300, EC 3.1.6.8). This is the precise, physiologically correct MF for ARSA and is independently supported by direct assay. Reason: Automated RHEA/EC mapping matches the experimentally established reaction and the IDA/EXP annotations below. Supporting Evidence: file:human/ARSA/ARSA-uniprot.txt cerebroside-3-sulfate (sulfatide) into cerebroside and sulfate, a |
| GO:0005764 lysosome | IEA GO_REF:0000044 | ACCEPT | Summary: ARSA is a lysosomal acid hydrolase; the lysosome is its functional site of action. Consistent with the SubCell mapping and with the experimentally supported lysosomal localization. Reason: Correct core localization for a lysosomal sulfatase; corroborated by TAS (PMID:2562955) and Reactome lysosomal-lumen annotations. Supporting Evidence: PMID:2562955 The arylsulfatase A was located in lysosome-like |
| GO:0005783 endoplasmic reticulum | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: ARSA transits the ER, where the catalytic Calpha-formylglycine is generated before lysosomal delivery. This is a maturation/transit compartment rather than the site of catalytic function. Reason: Real localization during biosynthesis (formylglycine generation and folding), but not where ARSA performs its physiological reaction; retained as non-core. Supporting Evidence: PMID:9342345 the oxidation of its thiol group to an aldehyde is catalyzed in the |
| GO:0005515 protein binding | IPI PMID:21516116 Next-generation sequencing to generate interactome datasets. | MARK AS OVER ANNOTATED | Summary: Bare protein-binding annotation from a high-throughput interactome-mapping study (Stitch-seq). Uninformative about ARSA molecular function. Reason: Generic protein binding from a systematic interactome screen; carries no specific functional information and is subsumed by the informative sulfatase MF terms. Supporting Evidence: PMID:21516116 Next-generation sequencing to generate interactome datasets. |
| GO:0005515 protein binding | IPI PMID:25416956 A proteome-scale map of the human interactome network. | MARK AS OVER ANNOTATED | Summary: Bare protein-binding annotation from a proteome-scale human interactome map. The interaction partner (TRIP13) does not inform ARSA's lysosomal sulfatase function. Reason: Generic protein binding from a large-scale interactome dataset; uninformative. Supporting Evidence: PMID:25416956 A proteome-scale map of the human interactome network. |
| GO:0005515 protein binding | IPI PMID:25910212 Widespread macromolecular interaction perturbations in human... | MARK AS OVER ANNOTATED | Summary: Bare protein-binding annotation from an interactome-perturbation study; uninformative about ARSA's molecular function. Reason: Generic protein binding from systematic interactome data. Supporting Evidence: PMID:25910212 Widespread macromolecular interaction perturbations in human genetic disorders. |
| GO:0005515 protein binding | IPI PMID:26871637 Widespread Expansion of Protein Interaction Capabilities by ... | MARK AS OVER ANNOTATED | Summary: Bare protein-binding annotation from an alternative-splicing interactome study; uninformative about ARSA function. Reason: Generic protein binding from a high-throughput splice-isoform interactome screen. Supporting Evidence: PMID:26871637 Widespread Expansion of Protein Interaction Capabilities by Alternative Splicing. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | MARK AS OVER ANNOTATED | Summary: Bare protein-binding annotations from the HuRI human binary interactome map (multiple partners including ANXA11, CCDC22, PKN1, TRIP13). None specify a functional molecular interaction relevant to ARSA's lysosomal sulfatase activity. Reason: Generic protein binding from a systematic binary interactome dataset; uninformative and subsumed by the specific sulfatase MF terms. Supporting Evidence: PMID:32296183 A reference map of the human binary protein interactome. |
| GO:0004065 arylsulfatase activity | IDA PMID:25553303 Ultra-performance liquid chromatography-tandem mass spectrom... | ACCEPT | Summary: Direct assay of leukocyte ARSA activity, including using a natural sulfatide substrate, measured by UPLC-MS/MS. Confirms arylsulfatase A enzymatic activity (EC 3.1.6.8) for the human protein. Reason: Experimental direct measurement of ARSA enzymatic activity; supports the core catalytic MF at the family level. Supporting Evidence: PMID:25553303 measuring arylsulfatase A (ARSA; EC3.1.6.8) activity PMID:25553303 using a natural sulfatide substrate |
| GO:0006689 ganglioside catabolic process | IDA PMID:11919180 Kidney sulfatides in mouse models of inherited glycosphingol... | KEEP AS NON CORE | Summary: In Arsa-null mice, ganglio-series sulfatides (e.g. SB1a) accumulate, showing ARSA is required to degrade sulfated members of the ganglio-series glycosphingolipid pathway. ARSA acts on the sulfated (sulfatide) members rather than on sialylated gangliosides per se, so this is an adjacent/peripheral role rather than the core function. Reason: Supported experimentally, but ARSA's direct chemistry is desulfation of galactosyl-3-sulfate glycolipids; its contribution to the ganglioside catabolic pathway is via the sulfated intermediates. Kept as non-core. Supporting Evidence: PMID:11919180 Arylsulfatase A is required to degrade SB1a. It is probably the sole PMID:11919180 sphingolipid-sulfatase cleaving the galactosyl-3-sulfate bond. |
| GO:0036021 endolysosome lumen | IC PMID:27498570 Endolysosomes Are the Principal Intracellular Sites of Acid ... | ACCEPT | Summary: Curator inference (IC) that ARSA, an acid hydrolase, is active in the endolysosome lumen, based on the finding that endolysosomes are the principal intracellular sites of acid hydrolase activity. Consistent with ARSA's lysosomal acid-pH-optimum activity. Reason: Correct localization of catalytic activity for an acid hydrolase; endolysosome lumen is a valid refinement of the lysosomal site of action. Supporting Evidence: PMID:27498570 endolysosomes are the principal organelles in |
| GO:0004098 cerebroside-sulfatase activity | IDA PMID:24294900 A new analytical bench assay for the determination of arylsu... | ACCEPT | Summary: Direct enzymatic assay of ARSA activity toward the natural substrate galactosyl-3-sulfate ceramide (sulfatide), establishing the physiological cerebroside-sulfatase reaction. This is the core molecular function. Reason: Direct assay against the natural sulfatide substrate; the specific, physiologically correct MF for ARSA. Supporting Evidence: PMID:24294900 galactosyl-3-sulfate ceramide (or sulfatide), is performed using neat sulfatide |
| GO:0030149 sphingolipid catabolic process | IDA PMID:32431092 Arylsulfatase A pseudodeficiency in Mexico: Enzymatic activi... | ACCEPT | Summary: ARSA deficiency leads to accumulation of cerebroside sulfate (sulfatide), placing ARSA in the sphingolipid (sulfatide) catabolic pathway. This is the correct core biological process for the enzyme. Reason: Sulfatide desulfation is the committed step of sulfatide degradation within sphingolipid catabolism; loss of ARSA blocks this catabolic route. Supporting Evidence: PMID:32431092 lead to the accumulation of cerebroside sulfate, a glycolipid that forms part of myelin membranes |
| GO:0004098 cerebroside-sulfatase activity | EXP PMID:10751093 Characterization of four arylsulfatase A missense mutations ... | ACCEPT | Summary: Functional characterization of MLD-causing missense mutants by expression and enzyme activity assays confirms that ARSA is the cerebroside-sulfatase whose deficiency causes metachromatic leukodystrophy. Reason: Experimental (mutant activity) support for ARSA's cerebroside-sulfatase function; a duplicate of the specific core MF and appropriately retained. Supporting Evidence: PMID:10751093 Metachromatic leukodystrophy is a lysosomal storage disease caused by the PMID:10751093 deficiency of arylsulfatase A. |
| GO:0005783 endoplasmic reticulum | EXP PMID:9342345 Conversion of cysteine to formylglycine: a protein modificat... | KEEP AS NON CORE | Summary: ARSA transits the ER, where the catalytic cysteine (Cys69) is oxidized to formylglycine before delivery to the lysosome. Experimental support for ER localization during maturation. Reason: Correct maturation compartment (formylglycine generation) but not the physiological site of catalysis; retained as non-core. Supporting Evidence: PMID:9342345 A linear sequence of 16 residues surrounding the Cys-69 |
| GO:0005576 extracellular region | TAS Reactome:R-HSA-6798751 | MARK AS OVER ANNOTATED | Summary: Extracellular localization attributed to neutrophil azurophil-granule exocytosis (Reactome degranulation pathway). This is a secretory-context/bystander location, not ARSA's functional lysosomal site. Reason: Peripheral to ARSA's role as an intracellular lysosomal sulfatase; captured only via a granule-exocytosis pathway. Supporting Evidence: Reactome:R-HSA-6798751 Exocytosis of azurophil granule lumen proteins |
| GO:0035578 azurophil granule lumen | TAS Reactome:R-HSA-6798751 | MARK AS OVER ANNOTATED | Summary: Localization to the neutrophil azurophil granule lumen (a lysosome-related organelle) from the Reactome degranulation pathway. Peripheral cell-type-specific location, not the core lysosomal function. Reason: Cell-type-specific granule membership from a degranulation pathway; not central to ARSA's function. Supporting Evidence: Reactome:R-HSA-6798751 Exocytosis of azurophil granule lumen proteins |
| GO:0070062 extracellular exosome | HDA PMID:23533145 In-depth proteomic analyses of exosomes isolated from expres... | MARK AS OVER ANNOTATED | Summary: Detection in urinary exosome proteomics. High-throughput proteomic identification in a secreted vesicle fraction; a bystander location rather than the functional site. Reason: Proteomic detection in exosomes is common for lysosomal/secreted proteins and does not reflect ARSA's core functional localization. Supporting Evidence: PMID:23533145 In-depth proteomic analyses of exosomes isolated from expressed prostatic secretions in urine. |
| GO:0005788 endoplasmic reticulum lumen | TAS Reactome:R-HSA-1614362 | KEEP AS NON CORE | Summary: ER lumen localization during biosynthesis, from the Reactome pathway in which SUMF1 generates the formylglycine that activates arylsulfatases. Maturation compartment, not the catalytic site. Reason: Consistent with ER formylglycine generation during maturation; non-core relative to lysosomal function. Supporting Evidence: Reactome:R-HSA-1614362 SUMF1 mediates the oxidation of cysteine to formylglycine, producing active arylsulfatases |
| GO:0005788 endoplasmic reticulum lumen | TAS Reactome:R-HSA-2248891 | KEEP AS NON CORE | Summary: ER lumen localization from the Reactome pathway describing M6PR-mediated transport of activated ARSA to the lysosome. Transit/maturation compartment. Reason: Maturation/transit location prior to lysosomal delivery; non-core. Supporting Evidence: Reactome:R-HSA-2248891 M6PR transports activated ARSA to the lysosome |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-1606807 | ACCEPT | Summary: Lysosomal lumen localization from the Reactome reaction in which ARSA removes sulfate from the PSAP(saposin B):sulfatide complex. This is the functional site of ARSA catalysis. Reason: Correct core functional compartment (lysosomal lumen) where ARSA acts on sulfatide with the saposin B activator. Supporting Evidence: Reactome:R-HSA-1606807 ARSA removes sulfate from PSAP(195-273):Sulfatide |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-2248891 | ACCEPT | Summary: Lysosomal lumen localization from the Reactome pathway describing delivery of activated ARSA to the lysosome via the mannose-6-phosphate receptor. Correct functional destination. Reason: Consistent with M6PR-mediated lysosomal targeting; the lysosomal lumen is ARSA's functional site. Supporting Evidence: Reactome:R-HSA-2248891 M6PR transports activated ARSA to the lysosome |
| GO:0043202 lysosomal lumen | TAS Reactome:R-HSA-9840949 | ACCEPT | Summary: Lysosomal lumen localization from the Reactome reaction in which ARSA removes sulfate from SM3 (a sulfated glycolipid), reinforcing the lysosomal lumen as the site of catalysis. Reason: Correct functional compartment; supports lysosomal-lumen localization of ARSA catalysis. Supporting Evidence: Reactome:R-HSA-9840949 ARSA removes sulfate from SM3 |
| GO:0005509 calcium ion binding | IDA PMID:12888274 Crystal structure of a covalent intermediate of endogenous h... | ACCEPT | Summary: The crystal structure of endogenous human ARSA shows a Ca2+ ion in the active site (one per subunit), coordinating the substrate sulfate and the catalytic formylglycine. Structural cofactor binding, not the core catalytic MF. Reason: Direct structural evidence for an active-site Ca2+; a genuine (non-core) cofactor binding function that supports catalysis. Supporting Evidence: PMID:12888274 present in the active site of arylsulfatase A isolated from human placenta is file:human/ARSA/ARSA-uniprot.txt Binds 1 Ca(2+) ion per subunit. |
| GO:0008484 sulfuric ester hydrolase activity | IDA PMID:15962010 Sulphatase activities are regulated by the interaction of su... | MARK AS OVER ANNOTATED | Summary: General sulfatase (sulfuric ester hydrolase) activity, whose generation depends on the SUMF1-catalyzed formylglycine modification (regulated by SUMF2). Correct but this is a broad parent MF subsumed by the specific arylsulfatase/cerebroside-sulfatase terms. Reason: True but overly general; the informative MF terms (GO:0004065, GO:0004098) already capture ARSA's sulfatase activity at greater specificity. Supporting Evidence: PMID:15962010 highly conserved cysteine located within their active site into formylglycine. |
| GO:0004065 arylsulfatase activity | TAS PMID:2562955 Cloning and expression of human arylsulfatase A. | ACCEPT | Summary: Cloning/expression paper establishing that the ARSA cDNA encodes arylsulfatase A enzymatic activity (up to 200-fold increase on transfection). Author-asserted MF. Reason: TAS support for ARSA arylsulfatase activity, consistent with the IDA/IBA MF annotations. Supporting Evidence: PMID:2562955 Transfection of monkey and baby hamster kidney cells resulted in an up to 200-fold increase of the arylsulfatase A activity. |
| GO:0005764 lysosome | TAS PMID:2562955 Cloning and expression of human arylsulfatase A. | ACCEPT | Summary: ARSA localizes to lysosomes and is delivered there in a mannose-6-phosphate receptor-dependent manner. Correct core localization. Reason: Author-asserted lysosomal localization consistent with M6PR-dependent targeting and the enzyme's acid-hydrolase role. Supporting Evidence: PMID:2562955 transported to dense lysosomes in a mannose 6-phosphate |
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Experiment: Quantitative substrate-profiling (lipidomics) of ARSA-deficient versus wild-type lysosomes to define the in vivo sulfated-glycolipid substrate range and the saposin-B dependence of each reaction.
Type: lipidomics
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