FADS3

The protein encoded by this gene is a member of the fatty acid desaturase (FADS) gene family. Desaturase enzymes regulate unsaturation of fatty acids through the introduction of double bonds between defined carbons of the fatty acyl chain. FADS family members are considered fusion products composed of an N-terminal cytochrome b5-like domain and a C-terminal multiple membrane-spanning desaturase portion, both of which are characterized by conserved histidine motifs. This gene is clustered with family members FADS1 and FADS2 at 11q12-q13.1; this cluster is thought to have arisen evolutionarily from gene duplication based on its similar exon/intron organization.

Fatty Acid Desaturase 3

Mammals have different sphingoid bases that differ in their length and/or pattern of desaturation and hydroxyl groups. The predominant sphingoid base in mammalian ceramides is sphing-4-enine (sphingosine or SPH) which has a trans desaturation at carbon 4. FADS3 is a ceramide desaturase that introduces a cis double bond between carbon 14 and carbon 15 of the SPH-containing ceramides, producing sphinga-4,14-dienine-containing ceramides (SPD ceramides). SPD ceramides occur widely in mammalian tissues and cells. Due to their unusual structure containing a cis double bond, SPD ceramides may have an opposite, negative role in lipid microdomain formation relative to conventional ceramides (PubMed:31916624).

FADS3 also acts as a methyl-end fatty acyl coenzyme A (CoA) desaturase that introduces a cis double bond between the preexisting double bond and the terminal methyl group of the fatty acyl chain. Desaturates (11E)-octadecenoate (trans-vaccenoate, the predominant trans fatty acid in human milk) at carbon 13 to generate (11E,13Z)-octadecadienoate (also known as conjugated linoleic acid 11E,13Z-CLA).

Sphingolipid metabolic process Source: UniProtKB-UniPathway
Unsaturated fatty acid biosynthetic process Source: UniProtKB

Endoplasmic reticulum membrane

Cytoplasmic: 1-133
Helical: 134-154
Lumenal: 155-159
Helical: 160-180
Cytoplasmic: 181-263
Helical: 264-284
Lumenal: 285-306
Helical: 307-327
Cytoplasmic: 328-445