Primary active transporter that auto-phosphorylates (hence P) at a key conserved aspartate residue, generating a conformational change that allows transport of the substrate. Hydrolysis of the phosphorylated Asp residue, catalyzed by the actuator (A) domain, results in another state with occluded substrates. Upon dissociation of Mg2+ and inorganic phosphate (Pi), the enzyme reverts to the initial state, in which the counter-transported substrate is released into the cytosol. [ http://www.ncbi.nlm.nih.gov/pubmed/25918123 http://www.ncbi.nlm.nih.gov/pubmed/18075584 ]