has participant hydron carbon dioxide L-serine zwitterion coenzyme A(4-) palmitoyl-CoA(4-) 3-dehydrosphinganinium(1+) serine C-palmitoyltransferase activity KEGG_REACTION:R01281 EC:2.3.1.50 molecular_function 3-oxosphinganine synthetase activity MetaCyc:SERINE-C-PALMITOYLTRANSFERASE-RXN RHEA:14761 SPT serine palmitoyltransferase Catalysis of the reaction: L-serine + H+ + palmitoyl-CoA = 3-dehydrosphinganine + CO2 + CoA. Reactome:R-HSA-428127 GO:0004758 C-palmitoyltransferase activity