Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Flicker, M. D. and Willmer, C. M. 1986. Vanadate sensitive ATPase and phosphatase activity in guard cell protoplasts of Commelina.-J. exp. Bot. 38: 642-648.Phosphatase activity was measured in extracts of guard cell protoplasts of Commelina communis L. using the artificial substrate p-nitrophenylphosphate. A pH optimum of 5.8 to 6.3 was determined. Ammonium molybdate (Ol mol m-3) and sodium vanadate (1-0 mol m-3) gave almost complete inhibition of phosphatase activity at pH 60. ATPase assays were, therefore, conducted in the presence of 0-2 mol m-3molybdate and vanadate was used as a specific inhibitor of plasmamembrane ATPase activity. Vanadate sensitive ATPase activity showed a pH optimum of 6.6 and activity was stimulated by KC1. These properties are characteristic of plasmamembrane proton pumping ATPases in other systems and suggest that proton extrusion in guard cells could be mediated by a similar enzyme. The maximum ATPase activity is sufficient to account for all the proton flux observed during the stomatal opening response. © 1987 Oxford University Press.

Original publication

DOI

10.1093/jxb/38.4.642

Type

Journal article

Journal

Journal of Experimental Botany

Publication Date

01/04/1987

Volume

38

Pages

642 - 648