Enables retinol isomerase activity and sphingolipid delta-4 desaturase activity. Acts upstream of or within ceramide biosynthetic process and positive regulation of apoptotic process. Predicted to be located in mitochondrion. Is expressed in several structures, including alimentary system; cardiovascular system; genitourinary system; nervous system; and sensory organ. Human ortholog(s) of this gene implicated in hypomyelinating leukodystrophy. Orthologous to human DEGS1 (delta 4-desaturase, sphingolipid 1). [provided by Alliance of Genome Resources, Apr 2022]