Lipid-binding START domain of mammalian STARD7 and related proteins
This subgroup includes the steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) domains of STARD7 (also known as gestational trophoblastic tumor 1/GTT1). It belongs to the START domain family, and in turn to the SRPBCC (START/RHO_alpha_C/PITP/Bet_v1/CoxG/CalC) domain superfamily of proteins that bind hydrophobic ligands. SRPBCC domains have a deep hydrophobic ligand-binding pocket. The gene encoding STARD7 is overexpressed in choriocarcinoma. STARD7 appears to be involved in the intracellular trafficking of phosphatidycholine (PtdCho) to mitochondria. STARD7 was shown to be surface active and to interact differentially with phospholipid monolayers, it showed a preference for phosphatidylserine, cholesterol, and phosphatidylglycerol.