PubMed:10984485
Annnotations
GlyCosmos6-Glycan-Motif-Image
{"project":"GlyCosmos6-Glycan-Motif-Image","denotations":[{"id":"T1","span":{"begin":25,"end":49},"obj":"Glycan_Motif"}],"attributes":[{"id":"A1","pred":"image","subj":"T1","obj":"https://api.glycosmos.org/wurcs2image/0.10.0/png/binary/G61418DU"}],"text":"The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.\nThe initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected."}
sentences
{"project":"sentences","denotations":[{"id":"T1","span":{"begin":0,"end":139},"obj":"Sentence"},{"id":"T2","span":{"begin":140,"end":316},"obj":"Sentence"},{"id":"T3","span":{"begin":317,"end":498},"obj":"Sentence"},{"id":"T4","span":{"begin":499,"end":706},"obj":"Sentence"},{"id":"T5","span":{"begin":707,"end":871},"obj":"Sentence"},{"id":"T6","span":{"begin":872,"end":1030},"obj":"Sentence"},{"id":"T7","span":{"begin":1031,"end":1244},"obj":"Sentence"},{"id":"T8","span":{"begin":1245,"end":1413},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.\nThe initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected."}
GlyCosmos6-Glycan-Motif-Structure
{"project":"GlyCosmos6-Glycan-Motif-Structure","denotations":[{"id":"T1","span":{"begin":25,"end":49},"obj":"https://glytoucan.org/Structures/Glycans/G61418DU"}],"text":"The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.\nThe initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected."}
Glycan-GlyCosmos
{"project":"Glycan-GlyCosmos","denotations":[{"id":"T1","span":{"begin":295,"end":301},"obj":"Glycan"},{"id":"T2","span":{"begin":534,"end":540},"obj":"Glycan"},{"id":"T3","span":{"begin":607,"end":613},"obj":"Glycan"},{"id":"T4","span":{"begin":861,"end":867},"obj":"Glycan"},{"id":"T5","span":{"begin":950,"end":956},"obj":"Glycan"},{"id":"T6","span":{"begin":975,"end":981},"obj":"Glycan"},{"id":"T7","span":{"begin":1107,"end":1113},"obj":"Glycan"},{"id":"T8","span":{"begin":1137,"end":1143},"obj":"Glycan"},{"id":"T9","span":{"begin":1262,"end":1268},"obj":"Glycan"},{"id":"T10","span":{"begin":1313,"end":1319},"obj":"Glycan"},{"id":"T11","span":{"begin":1357,"end":1363},"obj":"Glycan"}],"attributes":[{"id":"A1","pred":"glycosmos_id","subj":"T1","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A12","pred":"image","subj":"T1","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A2","pred":"glycosmos_id","subj":"T2","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A13","pred":"image","subj":"T2","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A3","pred":"glycosmos_id","subj":"T3","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A14","pred":"image","subj":"T3","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A4","pred":"glycosmos_id","subj":"T4","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A15","pred":"image","subj":"T4","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A5","pred":"glycosmos_id","subj":"T5","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A16","pred":"image","subj":"T5","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A6","pred":"glycosmos_id","subj":"T6","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A17","pred":"image","subj":"T6","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A7","pred":"glycosmos_id","subj":"T7","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A18","pred":"image","subj":"T7","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A8","pred":"glycosmos_id","subj":"T8","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A19","pred":"image","subj":"T8","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A9","pred":"glycosmos_id","subj":"T9","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A20","pred":"image","subj":"T9","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A10","pred":"glycosmos_id","subj":"T10","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A21","pred":"image","subj":"T10","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A11","pred":"glycosmos_id","subj":"T11","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A22","pred":"image","subj":"T11","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"}],"text":"The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.\nThe initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected."}
GlyCosmos15-UBERON
{"project":"GlyCosmos15-UBERON","denotations":[{"id":"T1","span":{"begin":469,"end":485},"obj":"Body_part"}],"attributes":[{"id":"A1","pred":"uberon_id","subj":"T1","obj":"http://purl.obolibrary.org/obo/UBERON_4200047"}],"text":"The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.\nThe initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected."}
sentences
{"project":"sentences","denotations":[{"id":"T1","span":{"begin":0,"end":139},"obj":"Sentence"},{"id":"T2","span":{"begin":140,"end":316},"obj":"Sentence"},{"id":"T3","span":{"begin":317,"end":498},"obj":"Sentence"},{"id":"T4","span":{"begin":499,"end":706},"obj":"Sentence"},{"id":"T5","span":{"begin":707,"end":871},"obj":"Sentence"},{"id":"T6","span":{"begin":872,"end":1030},"obj":"Sentence"},{"id":"T7","span":{"begin":1031,"end":1244},"obj":"Sentence"},{"id":"T8","span":{"begin":1245,"end":1413},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.\nThe initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected."}
GlyCosmos15-Sentences
{"project":"GlyCosmos15-Sentences","blocks":[{"id":"T1","span":{"begin":0,"end":139},"obj":"Sentence"},{"id":"T2","span":{"begin":140,"end":316},"obj":"Sentence"},{"id":"T3","span":{"begin":317,"end":498},"obj":"Sentence"},{"id":"T4","span":{"begin":499,"end":706},"obj":"Sentence"},{"id":"T5","span":{"begin":707,"end":871},"obj":"Sentence"},{"id":"T6","span":{"begin":872,"end":1030},"obj":"Sentence"},{"id":"T7","span":{"begin":1031,"end":1244},"obj":"Sentence"},{"id":"T8","span":{"begin":1245,"end":1413},"obj":"Sentence"}],"text":"The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.\nThe initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected."}
GlyCosmos15-Glycan
{"project":"GlyCosmos15-Glycan","denotations":[{"id":"T1","span":{"begin":295,"end":301},"obj":"Glycan"},{"id":"T2","span":{"begin":534,"end":540},"obj":"Glycan"},{"id":"T3","span":{"begin":607,"end":613},"obj":"Glycan"},{"id":"T4","span":{"begin":861,"end":867},"obj":"Glycan"},{"id":"T5","span":{"begin":950,"end":956},"obj":"Glycan"},{"id":"T6","span":{"begin":975,"end":981},"obj":"Glycan"},{"id":"T7","span":{"begin":1107,"end":1113},"obj":"Glycan"},{"id":"T8","span":{"begin":1137,"end":1143},"obj":"Glycan"},{"id":"T9","span":{"begin":1262,"end":1268},"obj":"Glycan"},{"id":"T10","span":{"begin":1313,"end":1319},"obj":"Glycan"},{"id":"T11","span":{"begin":1357,"end":1363},"obj":"Glycan"}],"attributes":[{"id":"A1","pred":"glycosmos_id","subj":"T1","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A2","pred":"glycosmos_id","subj":"T2","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A3","pred":"glycosmos_id","subj":"T3","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A4","pred":"glycosmos_id","subj":"T4","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A5","pred":"glycosmos_id","subj":"T5","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A6","pred":"glycosmos_id","subj":"T6","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A7","pred":"glycosmos_id","subj":"T7","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A8","pred":"glycosmos_id","subj":"T8","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A9","pred":"glycosmos_id","subj":"T9","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A10","pred":"glycosmos_id","subj":"T10","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A11","pred":"glycosmos_id","subj":"T11","obj":"https://glycosmos.org/glycans/show/G39738WL"},{"id":"A12","pred":"image","subj":"T1","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A13","pred":"image","subj":"T2","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A14","pred":"image","subj":"T3","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A15","pred":"image","subj":"T4","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A16","pred":"image","subj":"T5","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A17","pred":"image","subj":"T6","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A18","pred":"image","subj":"T7","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A19","pred":"image","subj":"T8","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A20","pred":"image","subj":"T9","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A21","pred":"image","subj":"T10","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"},{"id":"A22","pred":"image","subj":"T11","obj":"https://api.glycosmos.org/wurcs2image/latest/png/binary/G39738WL"}],"text":"The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.\nThe initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected."}
Lectin-Jamboree-Sentence
{"project":"Lectin-Jamboree-Sentence","blocks":[{"id":"T1","span":{"begin":0,"end":139},"obj":"Sentence"},{"id":"T2","span":{"begin":140,"end":316},"obj":"Sentence"},{"id":"T3","span":{"begin":317,"end":498},"obj":"Sentence"},{"id":"T4","span":{"begin":499,"end":706},"obj":"Sentence"},{"id":"T5","span":{"begin":707,"end":871},"obj":"Sentence"},{"id":"T6","span":{"begin":872,"end":1030},"obj":"Sentence"},{"id":"T7","span":{"begin":1031,"end":1244},"obj":"Sentence"},{"id":"T8","span":{"begin":1245,"end":1413},"obj":"Sentence"}],"text":"The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.\nThe initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected."}
Anatomy-UBERON
{"project":"Anatomy-UBERON","denotations":[{"id":"T1","span":{"begin":469,"end":485},"obj":"Body_part"}],"attributes":[{"id":"A1","pred":"uberon_id","subj":"T1","obj":"http://purl.obolibrary.org/obo/UBERON_4200047"}],"text":"The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.\nThe initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected."}