Catalytic component of a P4-ATPase flippase complex which catalyzes the hydrolysis of ATP coupled to the transport of aminophospholipids from the outer to the inner leaflet of various membranes and ensures the maintenance of asymmetric distribution of phospholipids (By similarity). Phospholipid translocation seems also to be implicated in vesicle formation and in uptake of lipid signaling molecules. In vitro, its ATPase activity is selectively and stereospecifically stimulated by phosphatidylserine (PS) (By similarity). The flippase complex ATP8A1:TMEM30A seems to play a role in regulation of cell migration probably involving flippase-mediated translocation of phosphatidylethanolamine (PE) at the plasma membrane (By similarity). Acts as aminophospholipid translocase at the plasma membrane in neuronal cells (By similarity). ATP + H2O + phospholipidSide 1 = ADP + phosphate + phospholipidSide 2. a 1,2-diacyl-sn-glycero-3-phospho-L-serine(out) + ATP + H2O = a 1,2-diacyl-sn-glycero-3-phospho-L-serine(in) + ADP + H(+) + phosphate Component of a P4-ATPase flippase complex which consists of a catalytic alpha subunit and an accessory beta subunit. Interacts with TMEM30A to form a flippase complex; this complex forms an intermediate phosphoenzyme. Interacts with TMEM30B; this interaction is reported conflictingly. Exit from the endoplasmic reticulum requires the presence of TMEM30A, but not TMEM30B. In the presence of TMEM30A, predominantly located in cytoplasmic punctate structures and localizes to the plasma membrane (By similarity). Localizes to plasma membranes of red blood cells (By similarity). Kidney. Cleaved by calpain in a caspase- and calcium influx-dependent manner during platelet apoptosis leading to a 100 kDa polypeptide. Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IV subfamily.