This is a family of phosphatidylserine decarboxylases, EC:4.1.1.65. These enzymes catalyze the reaction: Phosphatidyl-L-serine <=> phosphatidylethanolamine + CO2. Phosphatidylserine decarboxylase plays a central role in the biosynthesis of aminophospholipids by converting phosphatidylserine to phosphatidylethanolamine.