. "At the endoplasmic reticulum (ER) membrane, phosphatidylserine synthase 2 (PTDSS2) converts phosphatidylethanolamine (PE) into phosphatidylserine (PS) by facilitating the exchange of L-Serine (L-Ser) with the ethanolamine (ETA) head group (Saito et al. 1998, Tomohiro et al. 2009)."^^ . . . . .