The N-terminal domain of the V-ATPase subunit 'a' is regulated by pH in vitro and in vivo |
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Authors: | Dechant Reinhard Peter Matthias |
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Institution: | Institute of Biochemistry, Department of Biology, ETH Zurich, Competence Center for Systems Physiology and Metabolic Diseases, Zurich, Switzerland. reinhard.dechant@bc.biol.ethz.ch |
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Abstract: | Regulation of the activity of vacuolar ATPase (V-ATPase) is a well known, yet poorly understood phenomenon, which might underlie the contribution of V-ATPases in various cellular signaling processes.(1) In yeast, V-ATPase is regulated by glucose and contributes to activation of cAMP-dependent protein kinase A (PKA). We have recently shown that, in vivo, glucose regulates V-ATPase through cytosolic pH, suggesting that V-ATPase contains a pH sensitive subunit, which regulates assembly of the holo-complex.(2) Here, we present the purification and biochemical characterization of the N-terminal domain of subunit 'a', Vph1N, which has been suggested to act as a pH sensor in mammalian cells.(3) Interestingly, our studies demonstrate pH-dependent oligomerization of this domain in vivo and in vitro. Moreover, we identify a membrane proximal region that is required for the pH-dependent oligomerization, and suggest a speculative model for the regulation of the V-ATPase holo-complex by pH. |
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