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. May also participate in the establishment of the canalicular membrane integrity by ensuring asymmetric distribution of phospholipids in the canicular membrane (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. The flippase ATP8B1:TMEM30A complex can form an intermediate phosphoenzyme in vitro. Also interacts with beta subunit TMEM30B. Exit from the endoplasmic reticulum requires the presence of TMEM30A or TMEM30B. Localizes to apical membranes in epithelial cells. Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IV subfamily.