Plays a role in regulating membrane trafficking of cargo proteins, namely endosome to plasma membrane recycling and endosome to trans-Golgi network retrograde transport (PubMed:27733620, PubMed:30213940). 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 (PubMed:30213940). Appears to be implicated in intercellular communication by negatively regulating the release of exosomes (PubMed:30947313). The flippase activity towards membrane lipids and its role in membrane asymmetry remains to be proved (PubMed:30947313). 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 (PubMed:21914794). Transiently expressed in the plasma membrane (PubMed:30947313). Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IV subfamily.