Beta-D-Glucuronide Glucuronosohydrolase (beta-GLUCURONIDASE) Active Protein

This gene encodes a hydrolase that degrades glycosaminoglycans, including heparan sulfate, dermatan sulfate, and chondroitin-4,6-sulfate. The enzyme forms a homotetramer that is localized to the lysosome. Mutations in this gene result in mucopolysaccharidosis type VII. There are many pseudogenes of this locus in the human genome.

Function: Plays an important role in the degradation of dermatan and keratan sulfates.

Catalytic activity: A beta-D-glucuronoside + H2O = D-glucuronate + an alcohol.

Enzyme regulation: Inhibited by L-aspartic acid.

Subunit structure: Homotetramer.

Subcellular location: Lysosome.

Post-translational modification: N-linked glycosylated with 3 to 4 oligosaccharide chains. Ref.11 Ref.12 Ref.13

Involvement in disease: Defects in GUSB are the cause of mucopolysaccharidosis type 7 (MPS7) [

MIM:253220]; also known as Sly syndrome. MPS7 is an autosomal recessive lysosomal storage disease characterized by inability to degrade glucuronic acid-containing glycosaminoglycans. The phenotype is highly variable, ranging from severe lethal hydrops fetalis to mild forms with survival into adulthood. Most patients with the intermediate phenotype show hepatomegaly, skeletal anomalies, coarse facies, and variable degrees of mental impairment. Ref.16 Ref.17 Ref.18 Ref.19 Ref.20 Ref.21 Ref.22 Ref.23 Ref.24 Ref.25 Ref.26 Ref.27 Ref.28Note=Mucopolysaccharidosis type 7 is associated with non-immune hydrops fetalis, a generalized edema of the fetus with fluid accumulation in the body cavities due to non-immune causes. Non-immune hydrops fetalis is not a diagnosis in itself but a symptom, a feature of many genetic disorders, and the end-stage of a wide variety of disorders.

Sequence similarities: Belongs to the glycosyl hydrolase 2 family.