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N-acetylglucosamine-1-phosphodiester alpha-N-acetylglucosaminidase (phosphodiester alpha-GlcNAcase, mannose 6-phosphate-uncovering enzyme, NAGPA)
Function:
1) protein glycosylation
2) catalyzes 2nd step in formation of mannose 6-phosphate targeting signal on lysosomal enzyme oligosaccharides by removing GlcNAc residues from GlcNAc-alpha-P-mannose moieties, which are formed in the 1st step
glycoprotein N-acetyl-D-glucosaminyl-phospho-D-mannose + H2O
N-acetyl-D-glucosamine + glycoprotein phospho-D-mannose
Structure:
- homotetramer arranged as two disulfide-linked homodimers
- Tyr-based internalization signal may be essential for its retrieval from the plasma membrane to the trans-Golgi
- C-terminal NPFKD sequence may be endocytosis signal acting at plasma membrane or trans-Golgi to return the enzyme to the cis/medial-Golgi
- contains 1 EGF-like domain
Compartment: cis/medial Golgi
Alternative splicing: named isoforms=3
Expression: may be brain specific
General
glycoprotein
glycosidase (glycoside hydrolase)
membrane protein
Properties
SIZE: MW = 56 kD
entity length = 515 aa
COMPARTMENT: golgi
MOTIF: signal sequence {1-24}
N-glycosylation site {N208}
N-glycosylation site {N214}
N-glycosylation site {N296}
EGF domain {358-390}
MOTIF: cysteine residue {C362}
MODIFICATION: cysteine residue {C373}
N-glycosylation site {N366}
cysteine residue {C373}
MODIFICATION: cysteine residue {C362}
cysteine residue {C380}
MODIFICATION: cysteine residue {C389}
N-glycosylation site {N388}
cysteine residue {C389}
MODIFICATION: cysteine residue {C380}
N-glycosylation site {N420}
transmembrane domain {449-469}
Tyrosine-based internalization {488-491}
NPF internalization {511-515}
Database Correlations
OMIM 607985
UniProt Q9UK23
PFAM correlations
ENZYME 3.1.4.45
References
UniProt :accession Q9UK23