Involved in transport of phospholipids. Contributes to transmembrane flipping of lipids. Requires an interaction with a protein of the ALIS family for activity. Specific for phosphatidylserine and has no activity with lysolipid, phosphatidylcholine or phosphatidylethanolamine. ATP + H2O + phospholipidSide 1 = ADP + phosphate + phospholipidSide 2. Interacts with ALIS1, ALIS3 and ALIS5 in a heterologous system. Requires the presence of an ALIS protein to exit the endoplasmic reticulum to the prevacuolar compartment. A number of isoforms are produced. According to EST sequences. The intracellular targeting signals and lipid specificity determinants reside in the catalytic ALA subunit. Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IV subfamily. Truncated N-terminus.