Abstract
The monoclonal antibody to the β-subunit of H+/K+-ATPase (mAbHKβ) cross-reacts with a protein that acts as a molecular chaperone for the structural maturation of sarcoplasmic reticulum (SR) Ca2+-ATPase. We partially purified a mAbHKβ-reactive 65-kDa protein from Xenopus ovary. After in-gel digestion and peptide sequencing, the 65-kDa protein was identified as methionine aminopeptidase II (MetAP2). The effects of MetAP2 on SR Ca2+-ATPase expression were examined by injecting the cRNA for MetAP2 into Xenopus oocytes. Immunoprecipitation and pulse-chase experiments showed that MetAP2 was transiently associated with the nascent SR Ca2+-ATPase. Synthesis of functional SR Ca2+-ATPase was facilitated by MetAP2 and prevented by injecting an antibody specific for MetAP2. These results suggest that MetAP2 acts as a molecular chaperone for SR Ca2+-ATPase synthesis.
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Acknowledgement
This work was supported by a University of Occupational and Environmental Health Grant for Advanced Research (to M. K.).
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Noguchi, S., Komiya, T., Eguchi, H. et al. Methionine Aminopeptidase II: A Molecular Chaperone for Sarcoplasmic Reticulum Calcium ATPase. J Membrane Biol 215, 105–110 (2007). https://doi.org/10.1007/s00232-007-9010-7
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DOI: https://doi.org/10.1007/s00232-007-9010-7