A0A7N5K4X9 · A0A7N5K4X9_AILME
- ProteinBeta-hexosaminidase subunit beta
- GeneHEXB
- StatusUniProtKB unreviewed (TrEMBL)
- Amino acids587 (go to sequence)
- Protein existenceInferred from homology
- Annotation score4/5
Function
function
Hydrolyzes the non-reducing end N-acetyl-D-hexosamine and/or sulfated N-acetyl-D-hexosamine of glycoconjugates, such as the oligosaccharide moieties from proteins and neutral glycolipids, or from certain mucopolysaccharides. The isozyme B does not hydrolyze each of these substrates, however hydrolyzes efficiently neutral oligosaccharide. Only the isozyme A is responsible for the degradation of GM2 gangliosides in the presence of GM2A. During fertilization is responsible, at least in part, for the zona block to polyspermy. Present in the cortical granules of non-activated oocytes, is exocytosed during the cortical reaction in response to oocyte activation and inactivates the sperm galactosyltransferase-binding site, accounting for the block in sperm binding to the zona pellucida.
Catalytic activity
- N-acetyl-beta-D-6-sulfogalactosaminyl-(1->4)-alpha-L-iduronyl-(1->3)-N-acetyl-D-6-sulfogalactosamine + H2O = alpha-L-iduronyl-(1->3)-N-acetyl-D-6-sulfogalactosamine + N-acetyl-D-6-sulfogalactosamineThis reaction proceeds in the forward direction.
- N-acetyl-beta-D-galactosaminyl-(1->4)-beta-D-3-sulfogalactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + H2O = a beta-D-3-sulfogalactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + N-acetyl-beta-D-galactosamineThis reaction proceeds in the forward direction.
- a ganglioside GM2 (d18:1(4E)) + H2O = a ganglioside GM3 (d18:1(4E)) + N-acetyl-beta-D-galactosamineThis reaction proceeds in the forward direction.
- a ganglioside GM2 + H2O = a ganglioside GM3 + N-acetyl-beta-D-galactosamineThis reaction proceeds in the forward direction.
- beta-D-GalNAc-(1->4)-alpha-L-IdoA-(1->3)-beta-D-GalNAc-4-sulfate-(1->4)-alpha-L-IdoA-(1->3)-D-GalNAc-4-sulfate + H2O = alpha-L-IdoA-(1->3)-beta-D-GalNAc-4-sulfate-(1->4)-alpha-L-IdoA-(1->3)-D-GalNAc-4-sulfate + N-acetyl-D-galactosamineThis reaction proceeds in the forward direction.
Features
Showing features for active site.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Active site | 436 | Proton donor | |||
GO annotations
Aspect | Term | |
---|---|---|
Cellular Component | cortical granule | |
Cellular Component | lysosome | |
Cellular Component | membrane | |
Molecular Function | beta-N-acetylhexosaminidase activity | |
Biological Process | carbohydrate metabolic process | |
Biological Process | ganglioside catabolic process | |
Biological Process | glycosaminoglycan metabolic process |
Keywords
- Molecular function
- Biological process
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended nameBeta-hexosaminidase subunit beta
- EC number
- Alternative names
Gene names
Organism names
- Taxonomic lineageEukaryota > Metazoa > Chordata > Craniata > Vertebrata > Euteleostomi > Mammalia > Eutheria > Laurasiatheria > Carnivora > Caniformia > Ursidae > Ailuropoda
Accessions
- Primary accessionA0A7N5K4X9
Proteomes
Subcellular Location
UniProt Annotation
GO Annotation
Keywords
- Cellular component
PTM/Processing
Keywords
- PTM
Interaction
Subunit
There are 3 forms of beta-hexosaminidase: hexosaminidase A is a heterodimer composed of one subunit alpha and one subunit beta (chain A and B); hexosaminidase B is a homodimer of two beta subunits (two chains A and B); hexosaminidase S is a homodimer of two alpha subunits. The composition of the dimer (isozyme A versus isozyme S) has a significant effect on the substrate specificity of the alpha subunit active site.
Structure
Family & Domains
Features
Showing features for region, compositional bias, domain.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Region | 1-175 | Disordered | |||
Compositional bias | 66-80 | Pro residues | |||
Compositional bias | 141-175 | Basic and acidic residues | |||
Domain | 181-259 | Beta-hexosaminidase eukaryotic type N-terminal | |||
Domain | 281-584 | Glycoside hydrolase family 20 catalytic | |||
Sequence similarities
Belongs to the glycosyl hydrolase 20 family.
Keywords
- Domain
Phylogenomic databases
Family and domain databases
Sequence
- Sequence statusComplete
- Length587
- Mass (Da)65,444
- Last updated2021-06-02 v1
- MD5 ChecksumE521E3D4DA597D5FECD2F1755A508506
Computationally mapped potential isoform sequences
There is 1 potential isoform mapped to this entry
Entry | Entry name | Gene name | Length | ||
---|---|---|---|---|---|
G1L108 | G1L108_AILME | HEXB | 524 |
Features
Showing features for compositional bias.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Compositional bias | 66-80 | Pro residues | |||
Compositional bias | 141-175 | Basic and acidic residues | |||
Keywords
- Technical term