STRUCTURE, FUNCTION AND REGULATION OF PLASMA-MEMBRANE H+-ATPASE

Most antigenic determinants of yeast ATPase are located within its N-terminal part. Amino acids 24-56, 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 com coleoptiles provides molecular support to the 'Acid growth' theory.