Catalytic component of a P4-ATPase flippase complex which catalyzes the hydrolysis of ATP coupled to the transport of aminophospholipids, phosphatidylserines (PS) and phosphatidylethanolamines (PE), from the outer to the inner leaflet of the plasma membrane (PubMed:25315773, PubMed:25947375, PubMed:26567335, PubMed:29799007, PubMed:30018401, PubMed:36300302). Does not show flippase activity toward phosphatidylcholine (PC) (PubMed:34403372). Contributes to the maintenance of membrane lipid asymmetry with a specific role in morphogenesis of muscle cells. In myoblasts, mediates PS enrichment at the inner leaflet of plasma membrane, triggering PIEZO1-dependent Ca2+ influx and Rho GTPases signal transduction, subsequently leading to the assembly of cortical actomyosin fibers and myotube formation (PubMed:29799007). May be involved in the uptake of farnesyltransferase inhibitor drugs, such as lonafarnib. {ECO:0000269|PubMed:15860663, ECO:0000269|PubMed:25315773, ECO:0000269|PubMed:25947375, ECO:0000269|PubMed:26567335, ECO:0000269|PubMed:29799007, ECO:0000269|PubMed:30018401, ECO:0000269|PubMed:34403372, ECO:0000269|PubMed:36300302, ECO:0000305}. This is the function of ENSG00000068650 (ATP11A, ATPase phospholipid transporting 11A).