Alpha-N-acetylgalactosaminidase

Alpha-N-acetylgalactosaminidase
Identifiers
EC number	3.2.1.49
CAS number	9025-35-8
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

Alpha-N-acetylgalactosaminidase is an enzyme that catalyzes the hydrolysis of terminal non-reducing N-acetyl-D-galactosamine residues in N-acetyl-α-D-galactosaminides. This enzyme is crucial in the degradation of glycoproteins and glycolipids, which are essential components of cell membranes and play significant roles in cell-cell communication and molecular recognition.

Function

Alpha-N-acetylgalactosaminidase is involved in the lysosomal degradation pathway. It specifically cleaves the terminal N-acetylgalactosamine residues from glycoproteins and glycolipids, facilitating their breakdown and recycling within the cell. This process is vital for maintaining cellular homeostasis and function.

Clinical significance

Deficiency in alpha-N-acetylgalactosaminidase activity is associated with a rare lysosomal storage disorder known as Schindler disease. This condition is characterized by the accumulation of glycopeptides and glycolipids in the lysosomes, leading to a range of symptoms including developmental delay, neurological impairment, and other systemic manifestations.

Structure

The enzyme is a glycoprotein itself and is typically found in the lysosomes of cells. It is encoded by the NAGA gene in humans, which is located on chromosome 22. The structure of alpha-N-acetylgalactosaminidase includes a catalytic domain that is responsible for its enzymatic activity.

Mechanism

Alpha-N-acetylgalactosaminidase functions by cleaving the glycosidic bond between the N-acetylgalactosamine and the rest of the glycoprotein or glycolipid. This reaction involves the addition of a water molecule (hydrolysis) to break the bond, releasing the N-acetylgalactosamine residue.

Research and applications

Research into alpha-N-acetylgalactosaminidase has implications for understanding and treating lysosomal storage disorders. Enzyme replacement therapy and gene therapy are potential strategies for addressing deficiencies in this enzyme. Additionally, understanding its role in glycoprotein metabolism can provide insights into various biological processes and diseases.

Also see

• Lysosomal storage disease
• Glycoprotein
• Enzyme replacement therapy
• Schindler disease