1.14.19.31	a (7Z,10Z,13Z,16Z)-docosa-7,10,13,16-tetraenoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4Z,7Z,10Z,13Z,16Z)-docosa-4,7,10,13,16-pentaenoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O	(2)	
1.14.19.31	a (7Z,10Z,13Z,16Z)-docosa-7,10,13,16-tetraenoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4Z,7Z,10Z,13Z,16Z)-docosa-4,7,10,13,16-pentaenoyl-[glycerolipid] + ferricytochrome b5 + 2 H2O	(1)	
1.14.19.31	a (7Z,10Z,13Z,16Z,19Z)-docosa-7,10,13,16,19-pentaenoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4Z,7Z,10Z,13Z,16Z,19Z)-docosa-4,7,10,13,16,19-hexaenoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O	(1)	
1.14.19.31	a (7Z,10Z,13Z,16Z,19Z)-docosa-7,10,13,16,19-pentaenoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4Z,7Z,10Z,13Z,16Z,19Z)-docosa-4,7,10,13,16,19-hexaenoyl-[glycerolipid] + ferricytochrome b5 + 2 H2O	(1)