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 (PubMed:20224745, PubMed:16618126). 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) (PubMed:20224745, PubMed:16618126). 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 (PubMed:23269685). Acts as aminophospholipid translocase at the plasma membrane in neuronal cells; the activity is associated with hippocampus-dependent learning (PubMed:22007859). May play a role in brain connectivity (PubMed:27287255). 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 ATPase activity is stimulated by phosphatidylserine (PS) and minimally by phosphatidylethanolamine (PE) (PubMed:16618126, PubMed:20224745). ATPase activity is inhibited by the vanadate and by the presence of calcium (PubMed:20224745). Component of a P4-ATPase flippase complex which consists of a catalytic alpha subunit and an accessory beta subunit (PubMed:23269685). Interacts with TMEM30A to form a flippase complex; this complex forms an intermediate phosphoenzyme (PubMed:23269685). Interacts with TMEM30B; this interaction is reported conflictingly (By similarity). Exit from the endoplasmic reticulum requires the presence of TMEM30A, but not TMEM30B. In the presence of TMEM30A, predominantly located in cytoplasmic punctate structures (By similarity). Localizes to plasma membranes of red blood cells (PubMed:16643453). Localizes predominantly in the intracellular membranes, rather than the plasma membrane of platelets (PubMed:30674456). Found in most tissues except liver and testis. Most abundant in brain and lung. Also detected in fetal tissues. Isoform 1 is expressed in brain. Isoform 2 and isoform 3 are expressed in reticulocytes (PubMed:16643453). Expressed in mouse hippocampus in both dentate gyrus (DG) and the CA3 regions. Expressed in both neuronal as well as non-neuronal cells within the DG (PubMed:27287255). Highly expressed in platelets (PubMed:30674456). Cleaved by calpain in a caspase- and calcium influx-dependent manner only during platelet apoptosis and may lead to inactivation. Mice overexpressing ATP8A1 in brain display an autistic-like behavior but no difference in hippocampus-dependent learning. Unlike the mice overexpressing ATP8A1,homozygous knockout mice for ATP8A1 do not show any deficits in sociability behavior. Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IV subfamily. Initial characterization studies with purified Atp8a1 enzyme demonstrated similar but distinct properties compared to the plasma membrane aminophospholipid flippase; however, the flippase complex accessory beta subunit was not included in the assays.