Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Electronic Gene Ontology annotations created by ARBA machine learning models
Combined Automated Annotation using Multiple IEA Methods
The cell-layer- and cell-type-specific distribution of GalNAc-transferases in the ocular surface epithelia is altered during keratinization.
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Immunofluorescence localisation of GalNAc-T1, -T2, -T3, -T4 and -T6 in normal and keratinised ocular surface epithelia using isoform-specific monoclonal antibodies, supporting the Golgi and perinuclear localisation annotations.
"Five monoclonal antibodies raised against the GalNAc-T1, -T2, -T3, -T4, and -T6 isoenzymes, were used for immunofluorescence microscopic localization according to standard protocols"
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States the pathway position of the family: addition of GalNAc to serine and threonine is the initial step in O-glycosylation.
"The initial step in O-glycosylation is the enzymatic addition of N-acetyl galactosamine (GalNAc) to serine and threonine residues by a large family of polypeptide GalNAc-transferases (GalNAc-Ts)"
Polypeptide GalNAc-transferase T3 and familial tumoral calcinosis. Secretion of fibroblast growth factor 23 requires O-glycosylation.
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Shows that FGF23 secretion requires O-glycosylation and that GalNAc-T3 selectively directs it at a proprotein convertase recognition motif. Cited on GALNT1 as a direct assay; the GALNT1 measurement is not visible in the cached abstract.
"GalNAc-T3 selectively directs O-glycosylation in a subtilisin-like proprotein convertase recognition sequence motif, which blocks processing of FGF23"
Defining the membrane proteome of NK cells.
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High-throughput proteomic definition of the NK cell membrane proteome, in which GALNT1 is detected as a membrane protein. Provides no compartment resolution.
"Defining the membrane proteome of NK cells"
UDP-N-acetyl-α-D-galactosamine:polypeptide N-acetylgalactosaminyltransferases: completion of the family tree.
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Survey completing the functional characterisation of the twenty-member human GalNAc-transferase family, reporting expression patterns and enzymatic activity for the remaining uncharacterised isoforms alongside established ones.
"The formation of mucin-type O-glycans is initiated by an evolutionarily conserved family of enzymes, the UDP-N-acetyl-α-D-galactosamine:polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts)"
N-terminome analyses underscore the prevalence of SPPL3-mediated intramembrane proteolysis among Golgi-resident enzymes and its role in Golgi enzyme secretion.
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Establishes SPPL3-mediated intramembrane proteolysis as a widespread route by which Golgi-resident enzymes are released from their membrane anchor and secreted, and validates GALNT2 (not GALNT1) by immunoblot as an SPPL3-dependent secreted substrate.
"secretion of select novel substrates such as the key mucin-type O-glycosylation enzyme GALNT2 is dependent on endogenous SPPL3 protease activity"
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Reports unique peptides mapping to GCNT1 among Golgi glycosylation enzymes whose abundance changes with SPPL3 expression, which is a lead for shedding of that enzyme rather than of GALNT1.
"we found unique peptides mapping to CHST14, GCNT1, B4GALNT1, MAN1C1 and XYLT2"
Purification and cDNA cloning of a human UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase.
cDNA cloning, expression, and chromosomal localization of a human UDP-GalNAc:polypeptide, N-acetylgalactosaminyltransferase.
Substrate specificities of three members of the human UDP-N-acetyl-alpha-D-galactosamine:Polypeptide N-acetylgalactosaminyltransferase family, GalNAc-T1, -T2, and -T3.
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Purified recombinant GalNAc-T1, -T2 and -T3 were assayed on short peptide and MUC1 tandem-repeat acceptors. The three enzymes have distinct but partly overlapping peptide specificities and react at different rates with individual sites in the MUC1 repeat.
"The enzymes have distinct but partly overlapping specificities with short peptide acceptor substrates"
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GalNAc-T1 is strict for UDP-GalNAc as donor, unlike GalNAc-T2 which can also use UDP-Gal with one acceptor.
"GalNAc-T1 and -T3 showed strict donor substrate specificities for UDP-GalNAc"
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Initiation of O-glycosylation in a cell is set by the repertoire of GalNAc-transferases expressed, not by any single isoform, which is the key constraint on transferring acceptor-specificity claims between paralogues.
"The results demonstrate that individual GalNAc-transferases have distinct activities and the initiation of O-glycosylation in a cell is regulated by a repertoire of GalNAc-transferases"
Localization of three human polypeptide GalNAc-transferases in HeLa cells suggests initiation of O-linked glycosylation throughout the Golgi apparatus.
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Localises endogenous and epitope-tagged human GalNAc-T1 to the Golgi apparatus by three independent methods (subcellular fractionation, immunofluorescence, immunoelectron microscopy), and shows roughly tenfold concentration in Golgi stacks.
"In this study, we have localized endogenous and epitope-tagged human GalNAc-T1, -T2 and -T3 to the Golgi apparatus in HeLa cells by subcellular fractionation, immunofluorescence and immunoelectron microscopy."
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GalNAc-transferases are distributed throughout the Golgi stack rather than restricted to the cis-Golgi, supporting the Golgi cisterna membrane assignment.
"We show that all three GalNAc-transferases are concentrated about tenfold in Golgi stacks over Golgi associated tubular-vesicular membrane structures."
Genomic organization and chromosomal localization of three members of the UDP-N-acetylgalactosamine: polypeptide N-acetylgalactosaminyltransferase family.
RAB6:GTP and BICD homodimers bind COPI-independent Golgi-to-ER retrograde cargo
RAB6:GTP displaces PAFAH1B1 from dynein:dynactin complex
Dynein drives COPI-independent retrograde traffic from the Golgi to the ER
GALNTs transfer GalNAc to Mucins to form Tn antigens
O-linked glycosylation of mucins
GalNAc is transferred onto 3a
OpenScientist hypothesis report: GALNT1 has extracellular region (GO:0005576)
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Independent blinded assessment returned weakly supported and recommended downgrading the annotation to non-core or removing it, on the grounds that it is IEA-only, auto-derived from an evidence-free UniProt keyword, and unsupported by any GALNT1-specific experiment.
"UniProt attaches that "Secreted" keyword **without any PubMed evidence** of its own"