Structure, function and regulation of plasma membrane H⁺‐ATPase

Abstract

Most antigenic determinants of yeast ATPase are located within its N-terminal part. Amino acids 2656, required for insertion at the plasma membrane, are highly accessible. The C-terminus behaves as a modulable auto-inhibitory domain in both yeast and plant ATPases. The expression of functional plant enzyme in yeast allows its mutational analysis. Plant tissues involved in active transport, such as the stomata guard cells, phloem, root epidermis and endodermis, are enriched in ATPase. One isoform is phloem-specific. The fact that auxin induces the synthesis of ATPase in corn coleoptiles provides molecular support to the 'Acid growth' theory.

The fusicoccin receptor of plants is a member of the 14‐3‐3 superfamily of eukaryotic regulatory proteins

“…This proves that the receptor is represented by the hydrophobic, and not by the hydrophilic, isoform(s) of the plasma membrane associated 14-3-3 proteins. The H'-ATPase, the target enzyme of FC action and a trans-membrane protein of known structure (for review see [20]), likewise was localized in the hydrophobic, detergent-insoluble protein fraction (Fig. 5C, lane p).…”

“…It appears possible, therefore, that the ligand-occupied receptor associates directly with this domain of the ATPase, thereby locking the enzyme in its active state (as can be achieved alter- natively by proteolytic removal of the autoinhibitory domain [20]). On the other hand, P-type ATPases are subject to regulation by phosphorylationldephosphorylation [20], and kinases have been implied in the function of several 143-3 proteins [12], providing another plausible model of FC action (regulation of a specific protein kinase). Further insight in the mechanism awaits the molecular cloning and functional analysis of the 14-3-3 isoform(s) comprising the FC receptor.…”

Exploration of the Effects of High Hydrostatic Pressure on Microbial Growth, Physiology and Survival: Perspectives from Piezophysiology

“…In yeast, the plasma membrane H þ -ATPase, Pma1, plays an essential role in cytoplasmic pH homeostasis by pumping out protons accumulated in the cytoplasm. 77) The yeast cell has a large acidic compartment, the vacuole, with an internal pH of around 6.0. Acidic vacuolar pH is maintained through the function of vacuolar H þ -ATPase (V-H þ -ATPase) on the vacuolar membrane by pumping in protons.…”

Altered Distribution of the Yeast Plasma Membrane H+-ATPase as a Feature of Vacuolar H+-ATPase Null Mutants

“…One is Pma1p, which functions in the plasma membrane, and the second is the V-ATPase, 1 which functions in the vacuolar system (2,3). Pma1p is an essential enzyme that provides the protonmotive force for the yeast plasma membrane and plays a major role in the pH homeostasis of the cell (4). The enzyme is capable of generating very high membrane potentials, and in the presence of permeant anions, pH gradients of more than 3 units are observed (5).…”

“…To maintain its proper activity as well as to prevent its deleterious activity in different aspects of the secretory pathway, its transport to the cell surface must be strictly controlled. The amount of Pma1p in the plasma membrane is also under strict control, and usually the enzyme is present at relatively constant amounts of 25-50% of the membrane proteins (4). Because of its importance for the viability of the cell, Pma1p was subjected to extensive studies aimed at understanding its mechanism of action as well as its potential as a drug target for antifungal agents (6).…”