Zinc Transporters, ZnT5 and ZnT7, Are Required for the Activation of Alkaline Phosphatases, Zinc-requiring Enzymes That Are Glycosylphosphatidylinositol-anchored to the Cytoplasmic Membrane

Numerous proteins are properly folded by binding with zinc during their itinerary in the biosynthetic-secretory pathway. Several transporters have been implicated in the zinc entry into secretory compartments from cytosol, but their precise roles are poorly understood. We report here that two zinc t...

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Published in:The Journal of biological chemistry 2005-01, Vol.280 (1), p.637-643
Main Authors: Suzuki, Tomoyuki, Ishihara, Kaori, Migaki, Hitoshi, Matsuura, Wataru, Kohda, Atsushi, Okumura, Katsuzumi, Nagao, Masaya, Yamaguchi-Iwai, Yuko, Kambe, Taiho
Format: Article
Language:English
Subjects:
Alkaline Phosphatase - genetics
Alkaline Phosphatase - metabolism
Animals
Biological Transport
Cation Transport Proteins - genetics
Cation Transport Proteins - metabolism
Cell Line
Enzyme Activation - genetics
Humans
Molecular Sequence Data
Zinc - metabolism
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Summary:Numerous proteins are properly folded by binding with zinc during their itinerary in the biosynthetic-secretory pathway. Several transporters have been implicated in the zinc entry into secretory compartments from cytosol, but their precise roles are poorly understood. We report here that two zinc transporters (ZnT5 and ZnT7) localized in the secretory apparatus are responsible for loading zinc to alkaline phosphatases (ALPs) that are glycosylphosphatidylinositol-anchored membrane proteins exposed to the extracellular site. Disruption of the ZnT5 gene in DT40 cells decreased the ALP activity to 45% of that in the wild-type cells. Disruption of the ZnT7 gene lowered the ALP activity only by 20%. Disruption of both genes markedly decreased the ALP activity to
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M411247200