InterPro domain: IPR005045

CDC50/LEM3 is a family of membrane proteins whose members include cell cycle control protein 50, alkylphosphocholine resistance protein LEM3, which is is required for phospholipid translocation across the plasma membrane in Saccharomyces cerevisiae [ 1 ], and several ALA-interacting subunits, which are plant proteins involved in lipid translocation and secretory vesicle formation [ 2 , 3 ]. CDC50 (also known as P4-ATPase flippase complex beta subunit TMEM30A) is an accessory 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. It is required for the proper folding, assembly and ER to Golgi exit of the ATP8A2:CDC50A flippase complex, which may be involved in regulation of neurite outgrowth, and, reconstituted to liposomes, predominantly transports phosphatidylserine (PS) and to a lesser extent phosphatidylethanolamine (PE). In complex with ATP8A1, may play a role in regulation of cell migration probably involving flippase-mediated translocation of phosphatidylethanolamine (PE) at the plasma membrane [ 4 ].

1. A novel membrane protein, Ros3p, is required for phospholipid translocation across the plasma membrane in Saccharomyces cerevisiae. J. Biol. Chem. 277, 37855-62
2. The Arabidopsis P4-ATPase ALA3 localizes to the golgi and requires a beta-subunit to function in lipid translocation and secretory vesicle formation. Plant Cell 20, 658-76
3. Intracellular targeting signals and lipid specificity determinants of the ALA/ALIS P4-ATPase complex reside in the catalytic ALA alpha-subunit. Mol Biol Cell 21, 791-801
4. Crystal structure of a human plasma membrane phospholipid flippase. J Biol Chem 295, 10180-10194