GUSB Gene: Beta-Glucuronidase – Function, Deficiency, and Clinical Significance
Comprehensive guide to the GUSB gene, its role in glycosaminoglycan metabolism, associated disorders like Sly syndrome, and its importance in cancer research.
Gene Information Card
| Symbol | GUSB |
|---|---|
| Full Name | Glucuronidase Beta |
| Gene Type | Protein coding |
| Chromosomal Location | 7q11.21 |
| NCBI Gene ID | 2990 ncbi.nlm.nih.gov/gene/2990 |
| Ensembl ID | ENSG00000169919 |
| UniProt ID | P08236 |
| OMIM ID | 611499 |
| HGNC ID | 4696 |
| Aliases | MPS7, beta-glucuronidase, BG |
Description
The GUSB gene encodes the enzyme beta-glucuronidase, a lysosomal hydrolase that catalyzes the degradation of glycosaminoglycans (GAGs) containing glucuronic acid, such as dermatan sulfate, heparan sulfate, and chondroitin sulfate. This enzyme is critical for the stepwise breakdown of these complex carbohydrates within the lysosome. Deficiencies in beta-glucuronidase activity lead to the accumulation of undegraded GAGs, causing the lysosomal storage disorder Mucopolysaccharidosis Type VII (MPS VII), also known as Sly syndrome. The GUSB protein is synthesized as a precursor that undergoes post-translational modifications, including glycosylation and proteolytic cleavage, to form the mature, active enzyme. It functions as a homotetramer and requires specific conditions for optimal activity. Beyond its role in lysosomal catabolism, beta-glucuronidase is also used as a reporter gene in molecular biology and has been studied for its potential role in various cancers.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Disease | Mechanism | Evidence |
| Mucopolysaccharidosis Type VII (MPS VII) / Sly syndrome | Loss-of-function mutations in the GUSB gene lead to a deficiency in beta-glucuronidase enzyme activity. This results in the progressive accumulation of undegraded glycosaminoglycans (dermatan sulfate, heparan sulfate, and chondroitin sulfate) within lysosomes, causing cellular dysfunction and multi-organ damage. | ClinVar, OMIM |
| Cancer (various types) | Altered expression and activity of beta-glucuronidase have been observed in several cancers. It may contribute to tumor progression by degrading the extracellular matrix, facilitating invasion and metastasis. Its expression is often used as a prognostic marker. | COSMIC, PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Tissue | nTPM | Level |
| Liver | High | High |
| Kidney | High | High |
| Spleen | Medium | Medium |
| Lung | Medium | Medium |
| Brain | Low | Low |
| Muscle | Low | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Cell Line | nTPM | Notes |
| HepG2 (Liver) | High | Expected high expression in liver-derived cells. |
| A549 (Lung) | Medium | Moderate expression in lung carcinoma cells. |
| MCF7 (Breast) | Low | Lower expression in breast cancer cell line. |
| K562 (Leukemia) | Low | Low expression in chronic myelogenous leukemia cells. |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| Variant | Type | Frequency | Effect |
| c.1159C>T (p.Arg387Ter) | Nonsense | Rare | Introduces a premature stop codon, leading to a truncated, non-functional protein and severe enzyme deficiency. |
| c.526C>T (p.Arg176Trp) | Missense | Rare | Amino acid substitution that disrupts the enzyme's active site or folding, reducing catalytic activity. |
| c.1170+1G>A | Splice site | Rare | Disrupts normal mRNA splicing, leading to aberrant transcripts and loss of functional protein. |
| c.1450G>A (p.Asp484Asn) | Missense | Rare | Alters a conserved residue, likely affecting protein stability or tetramerization, leading to reduced enzyme activity. |
Mutation functional classification
Loss of Function (LOF)
The vast majority of disease-causing GUSB mutations are loss-of-function. These mutations reduce or completely abolish beta-glucuronidase enzymatic activity, leading to the accumulation of glycosaminoglycans and the development of MPS VII. The severity of the disease correlates with the residual enzyme activity.
Gain of Function (GOF)
No gain-of-function mutations have been described for GUSB in the context of disease. The enzyme's role is primarily catabolic, and increased activity has not been linked to a specific genetic disorder.
Dominant Negative (DN)
MPS VII is inherited in an autosomal recessive pattern, meaning two mutant alleles are required for disease manifestation. A dominant-negative effect is not a recognized mechanism for GUSB mutations, as carriers with one functional allele typically have sufficient enzyme activity.
View complete mutation data：
Gene Ontology (GO)
| • hydrolase activity | • beta-glucuronidase activity |
| • glycosaminoglycan catabolic process | • lysosome |
| • carbohydrate metabolic process | • extracellular matrix disassembly |
Pathways
• Glycosaminoglycan degradation
• Lysosome
Protein Summary
Beta-glucuronidase is a lysosomal enzyme that exists as a homotetramer. It is synthesized as a precursor protein that is glycosylated and proteolytically processed to its mature form. The enzyme catalyzes the hydrolysis of beta-D-glucuronic acid residues from the non-reducing end of glycosaminoglycans. It has a pH optimum around 4.5, consistent with its lysosomal localization. The protein structure includes a TIM barrel domain that contains the active site. Mutations affecting the active site, protein folding, or tetramerization can lead to enzyme deficiency. Beta-glucuronidase is also used as a reporter gene in molecular biology due to its stable activity and ease of assay.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| GUSB Knockout HEK293 Cell Line | EDJ-KQ4034 | Human | 2990 | Details Get a Quote |
| GUSB Knockout A-549 Cell Line | EDJ-KQ27599 | Human | 2990 | Details Get a Quote |
| GUSB Knockout HCT 116 Cell Line | EDJ-KQ27601 | Human | 2990 | Details Get a Quote |
| GUSB Knockout HeLa Cell Line | EDJ-KQ27602 | Human | 2990 | Details Get a Quote |
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