UniProt functional annotation for Q9Y3R4



	UniProt functional annotation for Q9Y3R4

UniProt code: Q9Y3R4.

Organism: Homo sapiens (Human).

Taxonomy: Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo.

Function: Exo-alpha-sialidase that catalyzes the hydrolytic cleavage of the terminal sialic acid (N-acetylneuraminic acid, Neu5Ac) of a glycan moiety in the catabolism of glycolipids, glycoproteins and oligosacharides (PubMed:14613940, PubMed:22228546). Recognizes sialyl linkage positions of the glycan moiety as well as the supramolecular organization of the sialoglycoconjugate. Displays preference for alpha- (2->3)-sialylated GD1a and GT1B gangliosides over alpha-(2->8)- sialylated GD1b, in both monomeric forms and micelles. Hydrolyzes monomeric GM1 ganglioside, but has no activity toward the miscellar form (PubMed:14613940). Has lower sialidase activity for glycoproteins such as fetuin and TF/transferrin that carry a mixture of alpha-(2->3) and alpha-(2->6)-sialyl linkages. Cleaves milk oligosaccharide alpha- (2->3)-sialyllactose, but is inactive toward alpha-(2->6)-sialyllactose isomer. Has no activity toward colominic acid, a homomer of alpha- (2->8)-linked Neu5Ac residues (PubMed:14613940). {ECO:0000269|PubMed:14613940, ECO:0000269|PubMed:22228546}.

Catalytic activity: Reaction=Hydrolysis of alpha-(2->3)-, alpha-(2->6)-, alpha- (2->8)- glycosidic linkages of terminal sialic acid residues in oligosaccharides, glycoproteins, glycolipids, colominic acid and synthetic substrates.; EC=3.2.1.18; Evidence={ECO:0000269|PubMed:14613940, ECO:0000269|PubMed:22228546};

Catalytic activity: Reaction=ganglioside GD1a + H2O = ganglioside GM1 + N- acetylneuraminate; Xref=Rhea:RHEA:47832, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:82637, ChEBI:CHEBI:82639; Evidence={ECO:0000269|PubMed:14613940}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47833; Evidence={ECO:0000305|PubMed:14613940};

Catalytic activity: Reaction=ganglioside GM1 + H2O = ganglioside GA1 + N-acetylneuraminate; Xref=Rhea:RHEA:47872, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:82639, ChEBI:CHEBI:88069; Evidence={ECO:0000269|PubMed:14613940}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47873; Evidence={ECO:0000305|PubMed:14613940};

Catalytic activity: Reaction=ganglioside GT1b + H2O = ganglioside GD1b + N- acetylneuraminate; Xref=Rhea:RHEA:47828, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:82939, ChEBI:CHEBI:82940; Evidence={ECO:0000269|PubMed:14613940}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47829; Evidence={ECO:0000305|PubMed:14613940};

Catalytic activity: Reaction=ganglioside GD1b + H2O = ganglioside GM1 + N- acetylneuraminate; Xref=Rhea:RHEA:47876, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:82639, ChEBI:CHEBI:82939; Evidence={ECO:0000269|PubMed:14613940}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47877; Evidence={ECO:0000305|PubMed:14613940};

Catalytic activity: Reaction=ganglioside GD3 + H2O = ganglioside GM3 + N-acetylneuraminate; Xref=Rhea:RHEA:48120, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:79210, ChEBI:CHEBI:79214; Evidence={ECO:0000250|UniProtKB:Q9JMH3}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:48121; Evidence={ECO:0000250|UniProtKB:Q9JMH3};

Catalytic activity: Reaction=ganglioside GM3 + H2O = beta-D-galactosyl-(1->4)-beta-D- glucosyl-(1<->1)-ceramide + N-acetylneuraminate; Xref=Rhea:RHEA:48136, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:79208, ChEBI:CHEBI:79210; Evidence={ECO:0000269|PubMed:14613940, ECO:0000269|PubMed:22228546}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:48137; Evidence={ECO:0000305|PubMed:14613940, ECO:0000305|PubMed:22228546};

Catalytic activity: Reaction=ganglioside GM2 + H2O = N-acetyl-beta-D-galactosaminyl-(1->4)- beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + N- acetylneuraminate; Xref=Rhea:RHEA:48172, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:79218, ChEBI:CHEBI:90085; Evidence={ECO:0000250|UniProtKB:Q9JMH3}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:48173; Evidence={ECO:0000250|UniProtKB:Q9JMH3};

Catalytic activity: Reaction=a neolactoside IV(3)-alpha-NeuAc-nLc4Cer(d18:1(4E)) + H2O = a neolactoside nLc4Cer(d18:1(4E)) + N-acetylneuraminate; Xref=Rhea:RHEA:47852, ChEBI:CHEBI:15377, ChEBI:CHEBI:17006, ChEBI:CHEBI:35418, ChEBI:CHEBI:58665; Evidence={ECO:0000269|PubMed:14613940}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47853; Evidence={ECO:0000305|PubMed:14613940};

Catalytic activity: Reaction=H2O + N-acetyl-alpha-neuraminosyl-(2->3)-beta-D-galactosyl- (1->4)-D-glucose = lactose + N-acetylneuraminate; Xref=Rhea:RHEA:64640, ChEBI:CHEBI:15377, ChEBI:CHEBI:17716, ChEBI:CHEBI:35418, ChEBI:CHEBI:156068; Evidence={ECO:0000269|PubMed:14613940, ECO:0000269|PubMed:22228546}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:64641; Evidence={ECO:0000305|PubMed:14613940, ECO:0000305|PubMed:22228546};

Biophysicochemical properties: Kinetic parameters: KM=0.24 mM for ganglioside GM3 (in the presence of Triton X-100) {ECO:0000269|PubMed:14613940}; KM=0.14 mM for ganglioside GD1a (in the presence of Triton X-100) {ECO:0000269|PubMed:14613940}; KM=0.51 mM for ganglioside GD1b (in the presence of Triton X-100) {ECO:0000269|PubMed:14613940}; KM=0.38 mM for ganglioside GT1b (in the presence of Triton X-100) {ECO:0000269|PubMed:14613940}; KM=0.28 mM for neolactoside IV(3)-alpha-NeuAc-nLc4Cer(d18:1(4E)) (in the presence of Triton X-100) {ECO:0000269|PubMed:14613940}; KM=0.31 mM for alpha(2->3)-sialyllactose {ECO:0000269|PubMed:14613940}; Vmax=67 umol/min/mg enzyme toward ganglioside GM3 (in the presence of Triton X-100) {ECO:0000269|PubMed:14613940}; Vmax=322 umol/min/mg enzyme toward ganglioside GD1a (in the presence of Triton X-100) {ECO:0000269|PubMed:14613940}; Vmax=5.45 umol/min/mg enzyme toward ganglioside GD1b (in the presence of Triton X-100) {ECO:0000269|PubMed:14613940}; Vmax=190 umol/min/mg enzyme toward ganglioside GT1b (in the presence of Triton X-100) {ECO:0000269|PubMed:14613940}; Vmax=253 umol/min/mg enzyme toward ganglioside neolactoside IV(3)- alpha-NeuAc-nLc4Cer(d18:1(4E)) (in the presence of Triton X-100) {ECO:0000269|PubMed:14613940}; Vmax=10 umol/min/mg enzyme toward alpha(2->3)-sialyllactose {ECO:0000269|PubMed:14613940}; Vmax=12.7 umol/min/mg enzyme toward fetuin {ECO:0000269|PubMed:14613940}; Vmax=0.75 umol/min/mg enzyme toward TF/transferrin {ECO:0000269|PubMed:14613940}; Vmax=0.70 umol/min/mg enzyme toward alpha-1-acid glycoprotein {ECO:0000269|PubMed:14613940}; pH dependence: Optimum pH is 5.6. {ECO:0000269|PubMed:14613940};

Subcellular location: Cytoplasm, cytosol {ECO:0000269|PubMed:10561456}.

Tissue specificity: Expressed in skeletal muscle, fetal liver and embryonic carcinoma cell line NT2-D1. {ECO:0000269|PubMed:10191093}.

Similarity: Belongs to the glycosyl hydrolase 33 family. {ECO:0000305}.

Annotations taken from UniProtKB at the EBI.


Organism:		Homo sapiens (Human).
Taxonomy:		Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo.



Function:		Exo-alpha-sialidase that catalyzes the hydrolytic cleavage of the terminal sialic acid (N-acetylneuraminic acid, Neu5Ac) of a glycan moiety in the catabolism of glycolipids, glycoproteins and oligosacharides (PubMed:14613940, PubMed:22228546). Recognizes sialyl linkage positions of the glycan moiety as well as the supramolecular organization of the sialoglycoconjugate. Displays preference for alpha- (2->3)-sialylated GD1a and GT1B gangliosides over alpha-(2->8)- sialylated GD1b, in both monomeric forms and micelles. Hydrolyzes monomeric GM1 ganglioside, but has no activity toward the miscellar form (PubMed:14613940). Has lower sialidase activity for glycoproteins such as fetuin and TF/transferrin that carry a mixture of alpha-(2->3) and alpha-(2->6)-sialyl linkages. Cleaves milk oligosaccharide alpha- (2->3)-sialyllactose, but is inactive toward alpha-(2->6)-sialyllactose isomer. Has no activity toward colominic acid, a homomer of alpha- (2->8)-linked Neu5Ac residues (PubMed:14613940). {ECO:0000269\|PubMed:14613940, ECO:0000269\|PubMed:22228546}.


Catalytic activity:		Reaction=Hydrolysis of alpha-(2->3)-, alpha-(2->6)-, alpha- (2->8)- glycosidic linkages of terminal sialic acid residues in oligosaccharides, glycoproteins, glycolipids, colominic acid and synthetic substrates.; EC=3.2.1.18; Evidence={ECO:0000269\|PubMed:14613940, ECO:0000269\|PubMed:22228546};
Catalytic activity:		Reaction=ganglioside GD1a + H2O = ganglioside GM1 + N- acetylneuraminate; Xref=Rhea:RHEA:47832, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:82637, ChEBI:CHEBI:82639; Evidence={ECO:0000269\|PubMed:14613940}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47833; Evidence={ECO:0000305\|PubMed:14613940};
Catalytic activity:		Reaction=ganglioside GM1 + H2O = ganglioside GA1 + N-acetylneuraminate; Xref=Rhea:RHEA:47872, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:82639, ChEBI:CHEBI:88069; Evidence={ECO:0000269\|PubMed:14613940}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47873; Evidence={ECO:0000305\|PubMed:14613940};
Catalytic activity:		Reaction=ganglioside GT1b + H2O = ganglioside GD1b + N- acetylneuraminate; Xref=Rhea:RHEA:47828, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:82939, ChEBI:CHEBI:82940; Evidence={ECO:0000269\|PubMed:14613940}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47829; Evidence={ECO:0000305\|PubMed:14613940};
Catalytic activity:		Reaction=ganglioside GD1b + H2O = ganglioside GM1 + N- acetylneuraminate; Xref=Rhea:RHEA:47876, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:82639, ChEBI:CHEBI:82939; Evidence={ECO:0000269\|PubMed:14613940}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47877; Evidence={ECO:0000305\|PubMed:14613940};
Catalytic activity:		Reaction=ganglioside GD3 + H2O = ganglioside GM3 + N-acetylneuraminate; Xref=Rhea:RHEA:48120, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:79210, ChEBI:CHEBI:79214; Evidence={ECO:0000250\|UniProtKB:Q9JMH3}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:48121; Evidence={ECO:0000250\|UniProtKB:Q9JMH3};
Catalytic activity:		Reaction=ganglioside GM3 + H2O = beta-D-galactosyl-(1->4)-beta-D- glucosyl-(1<->1)-ceramide + N-acetylneuraminate; Xref=Rhea:RHEA:48136, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:79208, ChEBI:CHEBI:79210; Evidence={ECO:0000269\|PubMed:14613940, ECO:0000269\|PubMed:22228546}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:48137; Evidence={ECO:0000305\|PubMed:14613940, ECO:0000305\|PubMed:22228546};
Catalytic activity:		Reaction=ganglioside GM2 + H2O = N-acetyl-beta-D-galactosaminyl-(1->4)- beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + N- acetylneuraminate; Xref=Rhea:RHEA:48172, ChEBI:CHEBI:15377, ChEBI:CHEBI:35418, ChEBI:CHEBI:79218, ChEBI:CHEBI:90085; Evidence={ECO:0000250\|UniProtKB:Q9JMH3}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:48173; Evidence={ECO:0000250\|UniProtKB:Q9JMH3};
Catalytic activity:		Reaction=a neolactoside IV(3)-alpha-NeuAc-nLc4Cer(d18:1(4E)) + H2O = a neolactoside nLc4Cer(d18:1(4E)) + N-acetylneuraminate; Xref=Rhea:RHEA:47852, ChEBI:CHEBI:15377, ChEBI:CHEBI:17006, ChEBI:CHEBI:35418, ChEBI:CHEBI:58665; Evidence={ECO:0000269\|PubMed:14613940}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:47853; Evidence={ECO:0000305\|PubMed:14613940};
Catalytic activity:		Reaction=H2O + N-acetyl-alpha-neuraminosyl-(2->3)-beta-D-galactosyl- (1->4)-D-glucose = lactose + N-acetylneuraminate; Xref=Rhea:RHEA:64640, ChEBI:CHEBI:15377, ChEBI:CHEBI:17716, ChEBI:CHEBI:35418, ChEBI:CHEBI:156068; Evidence={ECO:0000269\|PubMed:14613940, ECO:0000269\|PubMed:22228546}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:64641; Evidence={ECO:0000305\|PubMed:14613940, ECO:0000305\|PubMed:22228546};
Biophysicochemical properties:		Kinetic parameters: KM=0.24 mM for ganglioside GM3 (in the presence of Triton X-100) {ECO:0000269\|PubMed:14613940}; KM=0.14 mM for ganglioside GD1a (in the presence of Triton X-100) {ECO:0000269\|PubMed:14613940}; KM=0.51 mM for ganglioside GD1b (in the presence of Triton X-100) {ECO:0000269\|PubMed:14613940}; KM=0.38 mM for ganglioside GT1b (in the presence of Triton X-100) {ECO:0000269\|PubMed:14613940}; KM=0.28 mM for neolactoside IV(3)-alpha-NeuAc-nLc4Cer(d18:1(4E)) (in the presence of Triton X-100) {ECO:0000269\|PubMed:14613940}; KM=0.31 mM for alpha(2->3)-sialyllactose {ECO:0000269\|PubMed:14613940}; Vmax=67 umol/min/mg enzyme toward ganglioside GM3 (in the presence of Triton X-100) {ECO:0000269\|PubMed:14613940}; Vmax=322 umol/min/mg enzyme toward ganglioside GD1a (in the presence of Triton X-100) {ECO:0000269\|PubMed:14613940}; Vmax=5.45 umol/min/mg enzyme toward ganglioside GD1b (in the presence of Triton X-100) {ECO:0000269\|PubMed:14613940}; Vmax=190 umol/min/mg enzyme toward ganglioside GT1b (in the presence of Triton X-100) {ECO:0000269\|PubMed:14613940}; Vmax=253 umol/min/mg enzyme toward ganglioside neolactoside IV(3)- alpha-NeuAc-nLc4Cer(d18:1(4E)) (in the presence of Triton X-100) {ECO:0000269\|PubMed:14613940}; Vmax=10 umol/min/mg enzyme toward alpha(2->3)-sialyllactose {ECO:0000269\|PubMed:14613940}; Vmax=12.7 umol/min/mg enzyme toward fetuin {ECO:0000269\|PubMed:14613940}; Vmax=0.75 umol/min/mg enzyme toward TF/transferrin {ECO:0000269\|PubMed:14613940}; Vmax=0.70 umol/min/mg enzyme toward alpha-1-acid glycoprotein {ECO:0000269\|PubMed:14613940}; pH dependence: Optimum pH is 5.6. {ECO:0000269\|PubMed:14613940};
Subcellular location:		Cytoplasm, cytosol {ECO:0000269\|PubMed:10561456}.
Tissue specificity:		Expressed in skeletal muscle, fetal liver and embryonic carcinoma cell line NT2-D1. {ECO:0000269\|PubMed:10191093}.
Similarity:		Belongs to the glycosyl hydrolase 33 family. {ECO:0000305}.