Involved in the modulation of the mitochondrial apoptotic pathway by ensuring the accumulation of cardiolipin (CL) in mitochondrial membranes. In vitro, the TRIAP1:PRELID1 complex mediates the transfer of phosphatidic acid (PA) between liposomes and probably functions as a PA transporter across the mitochondrion intermembrane space to provide PA for CL synthesis in the inner membrane (PubMed:23931759). Likewise, the TRIAP1:PRELID3A complex mediates the transfer of phosphatidic acid (PA) between liposomes (in vitro) and probably functions as a PA transporter across the mitochondrion intermembrane space (in vivo) (PubMed:26071602). Mediates cell survival by inhibiting activation of caspase-9 which prevents induction of apoptosis (PubMed:15735003). a 1,2-diacyl-sn-glycero-3-phosphate(in) = a 1,2-diacyl-sn-glycero-3-phosphate(out) Monomer (PubMed:26071602). Interacts with APAF1 and HSP70 (PubMed:15735003). Forms a complex with PRELID1 in the mitochondrion intermembrane space (PubMed:23931759). Interacts with PRELID3A (PubMed:26071602). In p53/TP53-dependent manner in response to low levels of DNA damage. Not induced when DNA damage is severe. Belongs to the TRIAP1/MDM35 family. Truncated N-terminus.