alg6 (SPBC342.01c; UniProt O43053) encodes the Dol-P-Glc:Man9GlcNAc2-PP-Dol alpha-1,3-glucosyltransferase Alg6, which adds the first glucose. alg6 mutants transfer unglucosylated Man9GlcNAc2 to proteins and depend on UDP-Glc:glycoprotein glucosyltransferase (gpt1) for monoglucosylated glycans under ER stress. In the lumenal phase of dolichol-linked oligosaccharide (Glc3Man9GlcNAc2-PP-Dol) assembly on the ER membrane, it adds the next sugar to the growing precursor that oligosaccharyltransferase transfers to nascent glycoproteins. Function is assigned by orthology to the S. cerevisiae ALG enzymes.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000329 fungal-type vacuole membrane | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | KEEP AS NON CORE | Summary: ORFeome screen vacuolar membrane signal; Alg6 is an ER enzyme. Reason: Not the active location. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins |
| GO:0005789 endoplasmic reticulum membrane | IBA GO_REF:0000033 | ACCEPT | Summary: ER membrane: LLO assembly takes place on the ER membrane. Reason: UniProt places alg6 in the ER membrane by similarity to S. cerevisiae ALG6 (ECO:0000250|UniProtKB:Q12001) and flags it as a multi-pass membrane protein (predicted TRANSMEM segments); this is orthology plus topology prediction, consistent with the LLO assembly pathway that alg6 acts in, not a direct S. pombe localisation (the ORFeome screen recorded vacuolar-membrane and Golgi signal instead). Supporting Evidence: file:SCHPO/alg6/alg6-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane file:SCHPO/alg6/alg6-uniprot.txt Multi-pass membrane protein |
| GO:0005789 endoplasmic reticulum membrane | IEA GO_REF:0000044 | ACCEPT | Summary: ER membrane: LLO assembly takes place on the ER membrane. Reason: UniProt places alg6 in the ER membrane by similarity to S. cerevisiae ALG6 (ECO:0000250|UniProtKB:Q12001) and flags it as a multi-pass membrane protein (predicted TRANSMEM segments); this is orthology plus topology prediction, consistent with the LLO assembly pathway that alg6 acts in, not a direct S. pombe localisation (the ORFeome screen recorded vacuolar-membrane and Golgi signal instead). Supporting Evidence: file:SCHPO/alg6/alg6-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane file:SCHPO/alg6/alg6-uniprot.txt Multi-pass membrane protein |
| GO:0005789 endoplasmic reticulum membrane | ISS GO_REF:0000024 | ACCEPT | Summary: ER membrane: LLO assembly takes place on the ER membrane. Reason: UniProt places alg6 in the ER membrane by similarity to S. cerevisiae ALG6 (ECO:0000250|UniProtKB:Q12001) and flags it as a multi-pass membrane protein (predicted TRANSMEM segments); this is orthology plus topology prediction, consistent with the LLO assembly pathway that alg6 acts in, not a direct S. pombe localisation (the ORFeome screen recorded vacuolar-membrane and Golgi signal instead). Supporting Evidence: file:SCHPO/alg6/alg6-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane file:SCHPO/alg6/alg6-uniprot.txt Multi-pass membrane protein |
| GO:0005794 Golgi apparatus | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | KEEP AS NON CORE | Summary: ORFeome screen Golgi signal; Alg6 is an ER enzyme. Reason: Not the active location. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins |
| GO:0006487 protein N-linked glycosylation | EXP PMID:27587357 The conundrum of UDP-Glc entrance into the yeast ER lumen. | ACCEPT | Summary: Alg6 glucosylation of LLO for N-glycosylation (curator, full text). Supporting Evidence: PMID:9813085 The alg6 mutant does not glucosy- late lipid-linked oligosaccharides and transfers Man9GlcNAc2 to nascent polypeptide chains |
| GO:0006487 protein N-linked glycosylation | IMP PMID:9813085 The UDP-Glc:Glycoprotein glucosyltransferase is essential fo... | ACCEPT | Summary: alg6 mutants transfer Man9GlcNAc2 instead of Glc3Man9GlcNAc2. Supporting Evidence: PMID:9813085 The alg6 mutant does not glucosy- late lipid-linked oligosaccharides and transfers Man9GlcNAc2 to nascent polypeptide chains |
| GO:0006488 dolichol-linked oligosaccharide biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference. Reason: PAINT placement is backed by S. pombe genetics, as the alg6 disruptant fails to glucosylate lipid-linked oligosaccharides (PMID:9813085), and UniProt curates the role in dolichol-linked oligosaccharide synthesis by similarity to S. cerevisiae ALG6 (Q12001). Supporting Evidence: file:SCHPO/alg6/alg6-uniprot.txt glucosyltransferase that operates in the biosynthetic pathway of PMID:9813085 alg6 mutant does not glucosy- late lipid-linked oligosaccharides |
| GO:0006488 dolichol-linked oligosaccharide biosynthetic process | IMP PMID:27587357 The conundrum of UDP-Glc entrance into the yeast ER lumen. | ACCEPT | Summary: alg6 mutants do not glucosylate LLOs. Supporting Evidence: PMID:9813085 The alg6 mutant does not glucosy- late lipid-linked oligosaccharides and transfers Man9GlcNAc2 to nascent polypeptide chains |
| GO:0006488 dolichol-linked oligosaccharide biosynthetic process | IMP PMID:9813085 The UDP-Glc:Glycoprotein glucosyltransferase is essential fo... | ACCEPT | Summary: alg6 mutants do not glucosylate LLOs. Supporting Evidence: PMID:9813085 The alg6 mutant does not glucosy- late lipid-linked oligosaccharides and transfers Man9GlcNAc2 to nascent polypeptide chains |
| GO:0009101 glycoprotein biosynthetic process | IMP PMID:34851357 A novel fission yeast platform to model N-glycosylation and ... | TOO GENERAL | Summary: Broad parent; platform mutants alter glycoprotein N-glycans, captured more specifically by LLO biosynthesis. Supporting Evidence: PMID:34851357 We constructed a platform of 16 Schizosaccharomyces pombe strains that synthesize all possible theoretical combinations of LLOs containing three to zero glucose (Glc) residues and nine to five mannose (Man) residues. |
| GO:0016758 hexosyltransferase activity | IEA GO_REF:0000002 | TOO GENERAL | Summary: Generic hexosyltransferase; the specific activity is annotated. Reason: The specific activity, dolichyl pyrophosphate Man9GlcNAc2 alpha-1,3-glucosyltransferase activity (GO:0042281), is asserted (ACCEPT) elsewhere in this review and entails this term. It rests on UniProt's by-similarity curation from S. cerevisiae ALG6, the ALG6/ALG8 domain (Pfam PF03155; the InterPro IPR004856 signature behind this row), and the S. pombe alg6 mutant, which fails to glucosylate lipid-linked oligosaccharides (PMID:9813085). Supporting Evidence: file:SCHPO/alg6/alg6-uniprot.txt adds the first glucose residue from dolichyl phosphate glucose (Dol-P- file:SCHPO/alg6/alg6-uniprot.txt Pfam; PF03155; Alg6_Alg8; 1. PMID:9813085 alg6 mutant does not glucosy- late lipid-linked oligosaccharides |
| GO:0042281 dolichyl pyrophosphate Man9GlcNAc2 alpha-1,3-glucosyltransferase activity | EXP PMID:27587357 The conundrum of UDP-Glc entrance into the yeast ER lumen. | ACCEPT | Summary: Alg6 activity (curator, full text). Supporting Evidence: PMID:9813085 The alg6 mutant does not glucosy- late lipid-linked oligosaccharides and transfers Man9GlcNAc2 to nascent polypeptide chains |
| GO:0042281 dolichyl pyrophosphate Man9GlcNAc2 alpha-1,3-glucosyltransferase activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference. Reason: The specific reaction is curated by UniProt by similarity to S. cerevisiae ALG6 (ECO:0000250|UniProtKB:Q12001), and the protein carries the ALG6/ALG8 glucosyltransferase domain (Pfam PF03155); in S. pombe, alg6 disruption abolishes LLO glucosylation (PMID:9813085), a genetic readout consistent with, but not a direct assay of, the enzyme activity. Supporting Evidence: file:SCHPO/alg6/alg6-uniprot.txt adds the first glucose residue from dolichyl phosphate glucose (Dol-P- file:SCHPO/alg6/alg6-uniprot.txt Pfam; PF03155; Alg6_Alg8; 1. PMID:9813085 alg6 mutant does not glucosy- late lipid-linked oligosaccharides |
| GO:0042281 dolichyl pyrophosphate Man9GlcNAc2 alpha-1,3-glucosyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Mapping. Reason: The specific reaction is curated by UniProt by similarity to S. cerevisiae ALG6 (ECO:0000250|UniProtKB:Q12001), and the protein carries the ALG6/ALG8 glucosyltransferase domain (Pfam PF03155); in S. pombe, alg6 disruption abolishes LLO glucosylation (PMID:9813085), a genetic readout consistent with, but not a direct assay of, the enzyme activity. Supporting Evidence: file:SCHPO/alg6/alg6-uniprot.txt adds the first glucose residue from dolichyl phosphate glucose (Dol-P- file:SCHPO/alg6/alg6-uniprot.txt Pfam; PF03155; Alg6_Alg8; 1. PMID:9813085 alg6 mutant does not glucosy- late lipid-linked oligosaccharides |
| GO:0042281 dolichyl pyrophosphate Man9GlcNAc2 alpha-1,3-glucosyltransferase activity | IMP PMID:9813085 The UDP-Glc:Glycoprotein glucosyltransferase is essential fo... | ACCEPT | Summary: alg6 mutants do not glucosylate LLOs. Supporting Evidence: PMID:9813085 The alg6 mutant does not glucosy- late lipid-linked oligosaccharides and transfers Man9GlcNAc2 to nascent polypeptide chains |
| GO:0042281 dolichyl pyrophosphate Man9GlcNAc2 alpha-1,3-glucosyltransferase activity | ISS GO_REF:0000024 | ACCEPT | Summary: Similarity. Reason: The specific reaction is curated by UniProt by similarity to S. cerevisiae ALG6 (ECO:0000250|UniProtKB:Q12001), and the protein carries the ALG6/ALG8 glucosyltransferase domain (Pfam PF03155); in S. pombe, alg6 disruption abolishes LLO glucosylation (PMID:9813085), a genetic readout consistent with, but not a direct assay of, the enzyme activity. Supporting Evidence: file:SCHPO/alg6/alg6-uniprot.txt adds the first glucose residue from dolichyl phosphate glucose (Dol-P- file:SCHPO/alg6/alg6-uniprot.txt Pfam; PF03155; Alg6_Alg8; 1. PMID:9813085 alg6 mutant does not glucosy- late lipid-linked oligosaccharides |
| GO:0098553 lumenal side of endoplasmic reticulum membrane | TAS PMID:9878760 The dolichol pathway of N-linked glycosylation. | ACCEPT | Summary: Lumenal-face LLO assembly steps (after flipping), using Dol-P-Man/Dol-P-Glc donors. Supporting Evidence: PMID:9878760 The oligosaccharide substrate for the N-linked protein glycosylation is assembled at the membrane of the endoplasmic reticulum. |
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