The function of Ensembl gene identifier ENSG00000174915 (PTDSS2, phosphatidylserine synthase 2) is as follows. Catalyzes a base-exchange reaction in which the polar head group of phosphatidylethanolamine (PE) or phosphatidylcholine (PC) is replaced by L-serine (PubMed:19014349). Catalyzes the conversion of phosphatatidylethanolamine and does not act on phosphatidylcholine (PubMed:19014349). Can utilize both phosphatidylethanolamine (PE) plasmalogen and diacyl PE as substrate and the latter is six times better utilized, indicating the importance of an ester linkage at the sn-1 position (By similarity). Although it shows no sn-1 fatty acyl preference, exhibits significant preference towards docosahexaenoic acid (22:6n-3) compared with 18:1 or 20:4 at the sn-2 position (By similarity). {ECO:0000250|UniProtKB:Q9Z1X2, ECO:0000269|PubMed:19014349}.