Plays a role in regulating membrane trafficking of cargo proteins, namely endosome to plasma membrane recycling and endosome to trans-Golgi network retrograde transport. In complex with MON2 and DOP1B, regulates SNX3 retromer-mediated endosomal sorting of WLS, a transporter of Wnt morphogens in developing tissues. Participates in the formation of endosomal carriers that direct WLS trafficking back to Golgi, away from lysosomal degradation. Appears to be implicated in intercellular communication by negatively regulating the release of exosomes. The flippase activity towards membrane lipids and its role in membrane asymmetry remains to be proved. ATP + H2O + phospholipidSide 1 = ADP + phosphate + phospholipidSide 2. Heterotrimer with MON2 and DOP1B; this complex regulates SNX3-retromer mediated endosomal sorting of WLS. Efficient exit from the endoplasmic reticulum does not require TMEM30A, nor TMEM30B. Transiently expressed in the plasma membrane. Found in most tissues except spleen. Most abundant in brain. Also detected in fetal tissues. Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IV subfamily.