Chondroitinase is a 522 amino acid protein that localizes to the lysosome and functions as an exohydrolase that is essential for the degradation of glycosaminoglycans, keratan sulfate and chondroitin 6-sulfate. Using calcium as a cofactor, Chondroitinase, which exists as a disulfide linked oligomer, catalyzes the hydrolysis of the 6-sulfate group on target substrates. Defects in the gene encoding Chondroitinase are the cause of mucopolysaccharidosis type 4A (MPS4A), an autosomal recessive lysosomal storage disease that is characterized by the intracellular accumulation of keratan sulfate and chondroitin-6-sulfate and is associated with dental anomalies, short stature and, in some cases, death in the second or third decade of life.
Function:
GALNS (N-acetylgalactosamine-6-sulfatase) is a lysosomal exohydrolase which catalyzes the hydrolysis of the 6-sulfate groups of the N-acetyl-D-galactosamine 6-sulfate units of chondroitin sulfate and of the D-galactose 6-sulfate units of keratan sulfate. Deficiencies of this enzyme lead to Morquio A syndrome, a lysosomal storage disorder.
Subunit:
Oligomer of disulfide linked 40- and 15 kDa polypeptides.
Subcellular Location:
Lysosome.
Post-translational modifications:
The conversion to 3-oxoalanine (also known as SLCformylglycine, FGly), of a serine or cysteine residue in prokaryotes and of a cysteine residue in eukaryotes, is critical for catalytic activity (By similarity).
DISEASE:
Defects in GALNS are the cause of mucopolysaccharidosis type 4A (MPS4A) [MIM:253000]; also known as Morquio A syndrome. MPS4A is a form of mucopolysaccharidosis type 4, an autosomal recessive lysosomal storage disease characterized by intracellular accumulation of keratan sulfate and chondroitin-6-sulfate. Key clinical features include short stature, skeletal dysplasia, dental anomalies, and corneal clouding. Intelligence is normal and there is no direct central nervous system involvement, although the skeletal changes may result in neurologic complications. There is variable severity, but patients with the severe phenotype usually do not survive past the second or third decade of life.
Similarity:
Belongs to the sulfatase family.
SWISS:
P34059
Gene ID:
2588
Database links:
Entrez Gene: 2588 Human
Entrez Gene: 50917 Mouse
Entrez Gene: 292073 Rat
Omim: 612222 Human
SwissProt: P34059 Human
SwissProt: Q571E4 Mouse
SwissProt: Q32KJ6 Rat
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