Murine UDP-GlcNAc:Lysosomal Enzyme N-Acetylglucosamine-1-phosphotransferase Lacking the γ-Subunit Retains Substantial Activity toward Acid Hydrolases
UDP-GlcNAc:lysosomal enzyme N -acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase) mediates the first step in the synthesis of the mannose 6-phosphate recognition marker on acid hydrolases. The transferase exists as anα 2 β 2 γ 2 hexameric complex with the α- and β-subunits der...
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Veröffentlicht in: | The Journal of biological chemistry 2007-09, Vol.282 (37), p.27198 |
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Hauptverfasser: | , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | UDP-GlcNAc:lysosomal enzyme N -acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase) mediates the first step in the synthesis of the mannose
6-phosphate recognition marker on acid hydrolases. The transferase exists as anα 2 β 2 γ 2 hexameric complex with the α- and β-subunits derived from a single precursor molecule. The catalytic function of the transferase
is attributed to the α- and β-subunits, whereas the γ-subunit is believed to be involved in the recognition of a conformation-dependent
protein determinant common to acid hydrolases. Using knock-out mice with mutations in either the α/β gene or the γ gene, we
show that disruption of the α/β gene completely abolishes phosphorylation of high mannose oligosaccharides on acid hydrolases
whereas knock-out of the γ gene results in only a partial loss of phosphorylation. These findings demonstrate that the α/β-subunits,
in addition to their catalytic function, have some ability to recognize acid hydrolases as specific substrates. This process
is enhanced by the γ-subunit. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M704067200 |