Enables L-serine-phosphatidylcholine phosphatidyltransferase activity and L-serine-phosphatidylethanolamine phosphatidyltransferase activity. Predicted to be involved in phosphatidylserine biosynthetic process. Predicted to act upstream of or within phospholipid biosynthetic process. Located in endoplasmic reticulum membrane. Is expressed in several structures, including alimentary system; central nervous system; genitourinary system; integumental system; and sensory organ. Human ortholog(s) of this gene implicated in Lenz-Majewski hyperostotic dwarfism. Orthologous to human PTDSS1 (phosphatidylserine synthase 1). [provided by Alliance of Genome Resources, Apr 2022]