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C-Terminal Deletion Analysis of Plant Plasma Membrane H⁺-ATPase: Yeast as a Model System for Solute Transport across the Plant Plasma Membrane
Birgitte Regenberg, José Manuel Villalba, Frank C. Lanfermeijer and Michael G. Palmgren
The Plant Cell
Vol. 7, No. 10 (Oct., 1995), pp. 1655-1666
Published by: American Society of Plant Biologists (ASPB)
Stable URL: http://www.jstor.org/stable/3870027
Page Count: 12
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The plasma membrane proton pump ( H+-ATPase) energizes solute uptake by secondary transporters. Wild-type Arabidopsis plasma membrane H+-ATPase (AHA2) and truncated H+-ATPases lacking 38, 51, 61, 66, 77, 92, 96, and 104 C-terminal amino acids were produced in yeast. All AHA2 species were correctly targeted to the yeast plasma membrane and, in addition, accumulated in internal membranes. Removal of 38 C-terminal residues from AHA2 produced a high-affinity state of plant H+-ATPase with a low K m value (0.1 mM) for ATP. Removal of an additional 12 amino acids from the C terminus resulted in a significant increase in molecular activity of the enzyme. There was a close correlation between molecular activity of the various plant H+-ATPase species and their ability to complement mutants of the endogenous yeast plasma membrane H+-ATPase (pma1). This correlation demonstrates that, at least in this heterologous host, activation of H+-ATPase is a prerequisite for proper energization of the plasma membrane.
The Plant Cell © 1995 American Society of Plant Biologists (ASPB)