preferred_name: 1-hexadecanoyl-2-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-methionine = 1-hexadecanoyl-2-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-homocysteine + H(+)