Alpha-Man-Ia (mas-1) is a Golgi glycoside hydrolase of family GH47 that trims alpha-1,2-linked mannose residues during N-glycan maturation. Its N-terminal membrane anchor presents the catalytic domain to the secretory-pathway lumen. Loss of the enzyme changes glycan proportions and causes Man8GlcNAc2 accumulation, while alternative processing routes retain substantial glycosylation.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000139 Golgi membrane | IBA GO_REF:0000033 | ACCEPT | Summary: Golgi residence fits the type-II glycan-processing enzyme. Reason: The mas-1 mutant glycan study identifies the product as Golgi mannosidase I; its N-terminal signal anchor and lumen-facing GH47 catalytic region support Golgi membrane association. The direct biochemical work independently establishes glycan trimming. Supporting Evidence: PMID:9654102 The mas-1 gene of Drosophila melanogaster encodes Golgi mannosidase I (MAS-1) |
| GO:0000139 Golgi membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Golgi residence fits the type-II glycan-processing enzyme. Reason: The mas-1 mutant glycan study identifies the product as Golgi mannosidase I; its N-terminal signal anchor and lumen-facing GH47 catalytic region support Golgi membrane association. The direct biochemical work independently establishes glycan trimming. Supporting Evidence: PMID:9654102 The mas-1 gene of Drosophila melanogaster encodes Golgi mannosidase I (MAS-1) |
| GO:0000139 Golgi membrane | ISS GO_REF:0000024 | ACCEPT | Summary: Golgi residence fits the type-II glycan-processing enzyme. Reason: The mas-1 mutant glycan study identifies the product as Golgi mannosidase I; its N-terminal signal anchor and lumen-facing GH47 catalytic region support Golgi membrane association. The direct biochemical work independently establishes glycan trimming. Supporting Evidence: PMID:9654102 The mas-1 gene of Drosophila melanogaster encodes Golgi mannosidase I (MAS-1) |
| GO:0004571 mannosyl-oligosaccharide 1,2-alpha-mannosidase activity | IBA GO_REF:0000033 | ACCEPT | Summary: The enzyme removes alpha-1,2-linked mannose from oligomannosidic N-glycans. Reason: Recombinant mas-1 is active toward oligomannosidic glycans, and mas-1 deletion causes Man8GlcNAc2 accumulation. Together these support the catalytic annotation on alpha-Man-Ia rather than transfer solely from a GH47 family label. Supporting Evidence: PMID:23979800 Some of the recombinant mannosidases were demonstrably active towards oligomannosidic glycans, specifically, the Co(II)-requiring ManIIb, two 'acidic' mannosidases and the class I mas-1 mannosidase. PMID:9654102 There is an accumulation of the Man8GlcNAc2 which is one of the substrates for the MAS-1 enzyme. |
| GO:0004571 mannosyl-oligosaccharide 1,2-alpha-mannosidase activity | IDA PMID:23979800 Characterisation of class I and II Ξ±-mannosidases from Droso... | ACCEPT | Summary: The enzyme removes alpha-1,2-linked mannose from oligomannosidic N-glycans. Reason: Recombinant mas-1 is active toward oligomannosidic glycans, and mas-1 deletion causes Man8GlcNAc2 accumulation. Together these support the catalytic annotation on alpha-Man-Ia rather than transfer solely from a GH47 family label. Supporting Evidence: PMID:23979800 Some of the recombinant mannosidases were demonstrably active towards oligomannosidic glycans, specifically, the Co(II)-requiring ManIIb, two 'acidic' mannosidases and the class I mas-1 mannosidase. PMID:9654102 There is an accumulation of the Man8GlcNAc2 which is one of the substrates for the MAS-1 enzyme. |
| GO:0004571 mannosyl-oligosaccharide 1,2-alpha-mannosidase activity | IEA GO_REF:0000120 | ACCEPT | Summary: The enzyme removes alpha-1,2-linked mannose from oligomannosidic N-glycans. Reason: Recombinant mas-1 is active toward oligomannosidic glycans, and mas-1 deletion causes Man8GlcNAc2 accumulation. Together these support the catalytic annotation on alpha-Man-Ia rather than transfer solely from a GH47 family label. Supporting Evidence: PMID:23979800 Some of the recombinant mannosidases were demonstrably active towards oligomannosidic glycans, specifically, the Co(II)-requiring ManIIb, two 'acidic' mannosidases and the class I mas-1 mannosidase. PMID:9654102 There is an accumulation of the Man8GlcNAc2 which is one of the substrates for the MAS-1 enzyme. |
| GO:0004571 mannosyl-oligosaccharide 1,2-alpha-mannosidase activity | IMP PMID:9654102 Mutant analysis reveals an alternative pathway for N-linked ... | ACCEPT | Summary: The enzyme removes alpha-1,2-linked mannose from oligomannosidic N-glycans. Reason: Recombinant mas-1 is active toward oligomannosidic glycans, and mas-1 deletion causes Man8GlcNAc2 accumulation. Together these support the catalytic annotation on alpha-Man-Ia rather than transfer solely from a GH47 family label. Supporting Evidence: PMID:23979800 Some of the recombinant mannosidases were demonstrably active towards oligomannosidic glycans, specifically, the Co(II)-requiring ManIIb, two 'acidic' mannosidases and the class I mas-1 mannosidase. PMID:9654102 There is an accumulation of the Man8GlcNAc2 which is one of the substrates for the MAS-1 enzyme. |
| GO:0004571 mannosyl-oligosaccharide 1,2-alpha-mannosidase activity | ISS GO_REF:0000024 | ACCEPT | Summary: The enzyme removes alpha-1,2-linked mannose from oligomannosidic N-glycans. Reason: Recombinant mas-1 is active toward oligomannosidic glycans, and mas-1 deletion causes Man8GlcNAc2 accumulation. Together these support the catalytic annotation on alpha-Man-Ia rather than transfer solely from a GH47 family label. Supporting Evidence: PMID:23979800 Some of the recombinant mannosidases were demonstrably active towards oligomannosidic glycans, specifically, the Co(II)-requiring ManIIb, two 'acidic' mannosidases and the class I mas-1 mannosidase. PMID:9654102 There is an accumulation of the Man8GlcNAc2 which is one of the substrates for the MAS-1 enzyme. |
| GO:0005509 calcium ion binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Calcium binding is a cofactor feature of the GH47 catalytic apparatus. Reason: The calcium-dependent GH47 mechanism makes this binding annotation reasonable; it is ancillary to glycan hydrolysis rather than a distinct calcium-signaling function. Supporting Evidence: PMID:23979800 Some of the recombinant mannosidases were demonstrably active towards oligomannosidic glycans, specifically, the Co(II)-requiring ManIIb, two 'acidic' mannosidases and the class I mas-1 mannosidase. |
| GO:0005783 endoplasmic reticulum | IBA GO_REF:0000033 | UNDECIDED | Summary: ER residence requires distinction from the established Golgi role. Reason: The experimentally supported role is Golgi N-glycan trimming. ER entry during biosynthesis does not establish persistent ER residence; the inherited ER annotation may reflect another GH47 branch, but the exact PAINT node and target trafficking evidence do not resolve that distinction here. Supporting Evidence: PMID:9654102 The mas-1 gene of Drosophila melanogaster encodes Golgi mannosidase I (MAS-1) |
| GO:0005975 carbohydrate metabolic process | IEA GO_REF:0000002 | MODIFY | Summary: N-glycan mannose trimming specifies the broad carbohydrate process. Reason: Man8GlcNAc2 accumulation in the mutant identifies a direct glycoprotein-processing role rather than undifferentiated carbohydrate metabolism. Proposed replacements: Golgi apparatus N-glycan mannose trimming Supporting Evidence: PMID:9654102 There is an accumulation of the Man8GlcNAc2 which is one of the substrates for the MAS-1 enzyme. |
| GO:0012505 endomembrane system | HDA PMID:19317464 Mapping organelle proteins and protein complexes in Drosophi... | KEEP AS NON CORE | Summary: The endomembrane-system assignment is consistent but broad. Reason: The organellar proteomics annotation is compatible with the independently established Golgi glycan-processing role. It does not resolve a vesicle lumen versus a membrane anchor. Supporting Evidence: PMID:9654102 The mas-1 gene of Drosophila melanogaster encodes Golgi mannosidase I (MAS-1) |
| GO:0016020 membrane | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Broad membrane membership is supported by the signal anchor. Reason: The type-II Golgi mannosidase has a membrane anchor; the specific Golgi membrane term better expresses its core location. Supporting Evidence: PMID:9654102 The mas-1 gene of Drosophila melanogaster encodes Golgi mannosidase I (MAS-1) |
| GO:0036503 ERAD quality control pathway | IBA GO_REF:0000033 | UNDECIDED | Summary: A dedicated ERAD role is not established for the Golgi-trimming enzyme. Reason: GH47 includes ER quality-control mannosidases as well as Golgi-processing enzymes. The target mutant and recombinant assays demonstrate N-glycan trimming but do not directly show degradation commitment or ERAD participation. This is a branch-specific functional uncertainty, not evidence that all GH47 proteins lack ERAD roles. Supporting Evidence: PMID:23979800 Some of the recombinant mannosidases were demonstrably active towards oligomannosidic glycans, specifically, the Co(II)-requiring ManIIb, two 'acidic' mannosidases and the class I mas-1 mannosidase. PMID:9654102 There is an accumulation of the Man8GlcNAc2 which is one of the substrates for the MAS-1 enzyme. |
| GO:1904381 Golgi apparatus N-glycan mannose trimming | IMP PMID:9654102 Mutant analysis reveals an alternative pathway for N-linked ... | ACCEPT | Summary: Golgi N-glycan mannose trimming is the direct biological process. Reason: The mutant glycan profile accumulates an enzyme substrate while retaining compensatory processing routes, establishing a normal contribution to mannose trimming without requiring lethality. Supporting Evidence: PMID:9654102 There is an accumulation of the Man8GlcNAc2 which is one of the substrates for the MAS-1 enzyme. |
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