Phosphatidylserine Synthase 2 (PTDSS2)

Phosphatidylserine (PS) accounts for 5 to 10% of cell membrane phospholipids. In addition to its role as a structural component, PS is involved in cell signaling, blood coagulation, and apoptosis. PS is synthesized by a calcium-dependent base-exchange reaction catalyzed by PS synthases (EC 2.7.8.8), like PTDSS2, that exchange L-serine for the polar head group of phosphatidylcholine (PC) or phosphatidylethanolamine (PE) .

Pss1 and Pss2 localized exclusively to the mitochondrial-associated membrane (MAM) subcompartment of the endoplasmic reticulum (ER) in rodent cell lines and in mouse liver. Mouse liver MAM used PC and PE as substrates for PS biosynthesis, whereas ER membranes used only PE.