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UniProt functional annotation for Q02745 | ||
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| UniProt code: Q02745. |
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| Organism: | |
Sus scrofa (Pig). |
| Taxonomy: | |
Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Laurasiatheria; Artiodactyla; Suina; Suidae; Sus. |
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| Function: | |
A beta-galactoside alpha2-3 sialyltransferase involved in terminal sialylation of glycoproteins and glycolipids (PubMed:19820709, PubMed:8288606). Catalyzes the transfer of sialic acid (N-acetyl- neuraminic acid; Neu5Ac) from the nucleotide sugar donor CMP-Neu5Ac onto acceptor Galbeta-(1->3)-GalNAc-terminated glycoconjugates through an alpha2-3 linkage (PubMed:19820709, PubMed:8288606). Adds sialic acid to the core 1 O-glycan, Galbeta-(1->3)-GalNAc-O-Ser/Thr, which is a major structure of mucin-type O-glycans (PubMed:19820709, PubMed:8288606). As part of a homeostatic mechanism that regulates CD8- positive T cell numbers, sialylates core 1 O-glycans of T cell glycoproteins, SPN/CD43 and PTPRC/CD45. Prevents premature apoptosis of thymic CD8-positive T cells prior to peripheral emigration, whereas in the secondary lymphoid organs controls the survival of CD8-positive memory T cells generated following a successful immune response (By similarity). Transfers sialic acid to asialofetuin, presumably onto Galbeta-(1->3)-GalNAc-O-Ser (PubMed:8288606). Sialylates GM1a, GA1 and GD1b gangliosides to form GD1a, GM1b and GT1b, respectively (PubMed:8288606) (By similarity). {ECO:0000250|UniProtKB:P54751, ECO:0000269|PubMed:19820709, ECO:0000269|PubMed:8288606}. |
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| Catalytic activity: | |
Reaction=a beta-D-galactosyl-(1->3)-N-acetyl-alpha-D-galactosaminyl derivative + CMP-N-acetyl-beta-neuraminate = an N-acetyl-alpha- neuraminyl-(2->3)-beta-D-galactosyl-(1->3)-N-acetyl-alpha-D- galactosaminyl derivative + CMP + H(+); Xref=Rhea:RHEA:21616, ChEBI:CHEBI:15378, ChEBI:CHEBI:57812, ChEBI:CHEBI:60377, ChEBI:CHEBI:133470, ChEBI:CHEBI:139596; EC=2.4.99.4; Evidence={ECO:0000269|PubMed:19820709, ECO:0000269|PubMed:8288606}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:21617; Evidence={ECO:0000305|PubMed:19820709, ECO:0000305|PubMed:8288606}; |
| Catalytic activity: | |
Reaction=CMP-N-acetyl-beta-neuraminate + ganglioside GM1 (d18:1(4E)) = CMP + ganglioside GD1a (d18:1(4E)) + H(+); Xref=Rhea:RHEA:18021, ChEBI:CHEBI:15378, ChEBI:CHEBI:57812, ChEBI:CHEBI:60377, ChEBI:CHEBI:77709, ChEBI:CHEBI:78445; EC=2.4.99.2; Evidence={ECO:0000269|PubMed:8288606}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:18022; Evidence={ECO:0000305|PubMed:8288606}; |
| Catalytic activity: | |
Reaction=CMP-N-acetyl-beta-neuraminate + ganglioside GM1 (d18:1(4E)/18:0) = CMP + ganglioside GD1a (18:1(4E)/18:0) + H(+); Xref=Rhea:RHEA:48248, ChEBI:CHEBI:15378, ChEBI:CHEBI:57812, ChEBI:CHEBI:60377, ChEBI:CHEBI:73110, ChEBI:CHEBI:90153; Evidence={ECO:0000250|UniProtKB:P54751}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:48249; Evidence={ECO:0000250|UniProtKB:P54751}; |
| Catalytic activity: | |
Reaction=CMP-N-acetyl-beta-neuraminate + ganglioside GA1 (d18:1(4E)) = CMP + ganglioside GM1b (d18:1(4E)) + H(+); Xref=Rhea:RHEA:47560, ChEBI:CHEBI:15378, ChEBI:CHEBI:27938, ChEBI:CHEBI:57812, ChEBI:CHEBI:60377, ChEBI:CHEBI:78568; Evidence={ECO:0000269|PubMed:8288606}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47561; Evidence={ECO:0000305|PubMed:8288606}; |
| Catalytic activity: | |
Reaction=CMP-N-acetyl-beta-neuraminate + ganglioside GD1b = CMP + ganglioside GT1b + H(+); Xref=Rhea:RHEA:48240, ChEBI:CHEBI:15378, ChEBI:CHEBI:57812, ChEBI:CHEBI:60377, ChEBI:CHEBI:82939, ChEBI:CHEBI:82940; Evidence={ECO:0000250|UniProtKB:P54751}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:48241; Evidence={ECO:0000250|UniProtKB:P54751}; |
| Pathway: | |
Protein modification; protein glycosylation. {ECO:0000305|PubMed:8288606}. |
| Pathway: | |
Glycolipid biosynthesis. {ECO:0000305|PubMed:8288606}. |
| Subcellular location: | |
Golgi apparatus, Golgi stack membrane {ECO:0000250|UniProtKB:Q11201}; Single-pass type II membrane protein {ECO:0000255}. Golgi apparatus, trans-Golgi network membrane {ECO:0000250|UniProtKB:Q11201}; Single-pass type II membrane protein {ECO:0000255}. Secreted. Note=Membrane-bound form in medial and trans cisternae of Golgi (By similarity). Secreted into the body fluid. {ECO:0000250|UniProtKB:Q11201}. |
| Tissue specificity: | |
The long isoform is abundant in salivary gland, liver, lung, and colon mucosa. Both long and short forms are detected in submaxillary salivary glands. |
| Ptm: | |
The soluble form derives from the membrane form by proteolytic processing. |
| Miscellaneous: | |
[Isoform Short]: Seems to lack a 40 residues internal segment. {ECO:0000305}. |
| Similarity: | |
Belongs to the glycosyltransferase 29 family. {ECO:0000305}. |
Annotations taken from UniProtKB at the EBI.