(11Z,14Z,17Z)-eicosatrienoyl-CoA + 2 Fe(II)-[cytochrome b5] + O2 + 2 H(+) = (5Z,11Z,14Z,17Z)-eicosatetraenoyl-CoA + 2 Fe(III)-[cytochrome b5] + 2 H2O
(11z,14z,17z)-eicosatrienoyl-coa + 2 fe(ii)-[cytochrome b5] + o2 + 2 h(+) = (5z,11z,14z,17z)-eicosatetraenoyl-coa + 2 fe(iii)-[cytochrome b5] + 2 h2o