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Planta

, Volume 204, Issue 3, pp 352–359 | Cite as

The plasma-membrane H+-ATPase from beet root is inhibited by a calcium-dependent phosphorylation

  • Bárbara Lino
  • Víctor M. Baizabal-Aguirre
  • Luis E. González de la Vara
Article

Abstract.

Several plasma-membrane proteins from beet root (Beta vulgaris L.) have been functionally incorporated into reconstituted proteoliposomes. These showed H+-ATPase activity, measured both as ATP hydrolysis and H+ transport. The proton-transport specific activity was 10 times higher than in plasma membranes, and was greatly stimulated by potassium and valinomycin. These proteoliposomes also showed calcium-regulated protein kinase activity. This kinase activity is probably due to a calmodulin-like domain protein kinase (CDPK), since two protein bands were recognized by antibodies against soybean and Arabidopsis CDPK. This kinase phosphorylated histone and syntide-2 in a Ca2+-dependent manner. Among the plasma-membrane proteins phosphorylated by this kinase, was the H+-ATPase. When the H+-ATPase was either prephosphorylated or assayed in the presence of Ca2+, both the ATP-hydrolysis and the proton-transport activities were slower. This inhibition was reversed by an alkaline-phosphatase treatment. A trypsin treatment (that has been reported to remove the C-terminal autoinhibitory domain from the H+-ATPase) also reversed the inhibition caused by phosphorylation. These results indicate that a Ca2+-dependent phosphorylation, probably caused by a CDPK, inhibits the H+-ATPase activities. The substrate of this regulatory phosphorylation could be the H+-ATPase itself, or a different protein influencing the ATPase activities.

Key words:Beta H+-ATPase Phosphorylation of proteins Plasma membrane Protein kinase 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Bárbara Lino
    • 1
  • Víctor M. Baizabal-Aguirre
    • 1
  • Luis E. González de la Vara
    • 1
  1. 1.Departamento de Biotecnología y Bioquímica, Unidad Irapuato, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, 36500 Irapuato, Gto, México

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