||The enzyme, which has been characterized from plants, fungi, and mammals, generates a trans double bond at position 4 of sphinganine bases in sphingolipids . The preferred substrate is dihydroceramide, but the enzyme is also active with dihydroglucosylceramide . Unlike EC 18.104.22.168, sphingolipid 8-desaturase, this enzyme does not contain an integral cytochrome b5 domain  and requires an external cytochrome b5 . The product serves as an important signalling molecules in mammals and is required for spermatide differentiation .
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