The plasma membrane H(+) ATPase of plants and fungi generates a proton gradient that drives the active transport of nutrients by H(+)-symport (PubMed:10748244, PubMed:12920605, PubMed:27013734). The resulting external acidification and/or internal alkinization may mediate growth responses (PubMed:10748244, PubMed:12920605). Involved in maintaining the membrane potential and delta-pH, together forming the plasma membrane protonmotive force (PMF) required for root and hypocotyl elongation and root tropism (PubMed:22214817, PubMed:24492258). Important for root growth and development during different nitrogen regimes (PubMed:25382626). Forms a functional cation-translocating unit with CNGC17 that is activated by PSKR1/BAK1 and possibly other BAK1/RLK complexes (PubMed:26071421). ATP + H(+)(in) + H2O = ADP + 2 H(+)(out) + phosphate Regulated by an auto-inhibitory C-terminal domain that can be displaced by phosphorylation of Thr-947 and the subsequent binding of 14-3-3 proteins (PubMed:10353834). Negatively regulated by PKS5 (PubMed:17483306). PKS5 phosphorylates Ser-931, inhibiting interaction with the activating 14-3-3 protein (PubMed:17483306). Positively regulated by PSY1R (PubMed:25267325). PSY1R phosphorylates Thr-881, situated in the auto-inhibitory region I of the C-terminal domain, causing pump activation (PubMed:25267325). Negatively regulated by the secreted peptide RALF (PubMed:24458638). After specific binding to FERONIA, RALF causes phosphorylation at Ser-899, mediating the inhibition of proton transport (PubMed:24458638). Activated by lysophospholipids, without the involvement of phosphorylation of Thr-947 (PubMed:25971968). This activation is critically dependent on the single autoinhibitory residue Leu-919 (PubMed:25971968). Repressed by PP2C-D phosphatases (e.g. PP2C67/PP2C-D1 and PP2C64/PP2C-D5) which dephosphorylates Thr-947 (PubMed:24858935). Triggered by SAUR19 via phosphorylation of the C-terminal autoinhibitory domain (e.g. Thr-947), as a result of the inhibition of PP2C67/PP2C-D1 (PubMed:24858935). Binds to 14-3-3 proteins (PubMed:10593986). The binding is induced by phosphorylation of Thr-947 and it activates the H(+)-ATPase (PubMed:10593986). Interacts (via the R-domain) with PSY1R (via C-terminus) (PubMed:25267325). Part of a functional complex containing PSKR1, BAK1, CNGC17, and AHA (PubMed:26071421). Interacts with CNGC17 and PSKR1 (PubMed:26071421). Interacts with PP2C67/PP2C-D1 at the plasma membrane (PubMed:24858935). A number of isoforms are produced. According to EST sequences. Higher levels in roots than in shoots (PubMed:2143186). Expressed in epidermal and root cortex cells, in phloem, xylem and root hairs (PubMed:17483306). Detected in cotyledons, hypocotyls, roots and root hairs (PubMed:25267325). Expressed on the surface of developing seeds and up to the early globular stage of embryo development. Up-regulated by low nitrate conditions. The C-terminus contains a R-domain composed of 2 autoinhibitory regions (863-885 and 904-919). Phosphorylation at Thr-881 by PSY1R (PubMed:17651370, PubMed:25267325). This phosphorylation activates proton pumping (PubMed:25267325). Decreased phosphorylation in response to flg22 elicitation (PubMed:17651370). Phosphorylation at Ser-899 is specifically induced by RALF1, thus leading to the inhibition of proton transport (PubMed:24458638). Increased phosphorylation in response to flg22 elicitation (PubMed:17651370). Phosphorylation of Thr-947 induces the binding to 14-3-3 proteins, but phosphorylation of Ser-931 interfers with this binding no matter whether Thr-947 is phosphorylated or not (PubMed:10593986, PubMed:17483306). Decreased phosphorylation in response to flg22 elicitation (PubMed:17651370). Phosphorylation of Thr-947 is enhanced by the presence of brassinolide (BL) via the BRI1-BIN2 pathway and prior the trigger of hypocotyl elongation (PubMed:30649552). Inactivated by PP2C67/PP2C-D1-mediated Thr-947 dephosphorylation; SAUR19 inhibits the action of PP2C67/PP2C-D1 and thus promotes the active phosphorylated form (PubMed:24858935). Abscisic acid induces dephosphorylation of AHA2 in etiolated seedlings, suppressing ATP hydrolysis and hypocotyl elongation. No visible phenotype under normal growth conditions, due to the redudancy with AHA1. Aha1 and aha2 double mutants are embryo lethal. The catalytic mechanism involves at least four different enzyme conformational states named E1, E1P, E2P, and E2, with the E1P-E2P transition accompanying the transfer of ion across the membrane. E1P and E2P are phosphorylated intermediates. Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IIIA subfamily.