Stearoyl-CoA desaturase (SCD; EC 220.127.116.11) is an iron-containing enzyme that catalyzes a rate-limiting step in the synthesis of unsaturated fatty acids. The principal product of SCD is oleic acid, which is formed by desaturation of stearic acid. The ratio of stearic acid to oleic acid has been implicated in the regulation of cell growth and differentiation through effects on cell membrane fluidity and signal transduction. Four SCD isoforms, Scd1 through Scd4, have been identified in mouse. In contrast, only 2 SCD isoforms, SCD1 and SCD5 (MIM 608370), have been identified in human. SCD1 shares about 85% amino acid identity with all 4 mouse SCD isoforms, as well as with rat Scd1 and Scd2. In contrast, SCD5 shares limited homology with the rodent SCDs and appears to be unique to primates.
Elevated expression levels of SCD1 is found to be correlated with obesity  and tumor malignancy. It is believed that tumor cells obtain most part of their requirement for fatty acids by de novo synthesis. This phenomenon depends on increased expression of fatty acid biosynthetic enzymes that produce required fatty acids in large quantities.
^Wang J, Yu L, Schmidt RE, Su C, Huang X, Gould K, Cao G (Jul 2005). "Characterization of HSCD5, a novel human stearoyl-CoA desaturase unique to primates". Biochemical and Biophysical Research Communications332 (3): 735–42. doi:10.1016/j.bbrc.2005.05.013. PMID15907797.
Samuel W, Kutty RK, Nagineni S, Gordon JS, Prouty SM, Chandraratna RA, Wiggert B (Aug 2001). "Regulation of stearoyl coenzyme A desaturase expression in human retinal pigment epithelial cells by retinoic acid". The Journal of Biological Chemistry276 (31): 28744–50. doi:10.1074/jbc.M103587200. PMID11397803.
Samuel W, Nagineni CN, Kutty RK, Parks WT, Gordon JS, Prouty SM, Hooks JJ, Wiggert B (Jan 2002). "Transforming growth factor-beta regulates stearoyl coenzyme A desaturase expression through a Smad signaling pathway". The Journal of Biological Chemistry277 (1): 59–66. doi:10.1074/jbc.M108730200. PMID11677241.
Choi Y, Park Y, Storkson JM, Pariza MW, Ntambi JM (Jun 2002). "Inhibition of stearoyl-CoA desaturase activity by the cis-9,trans-11 isomer and the trans-10,cis-12 isomer of conjugated linoleic acid in MDA-MB-231 and MCF-7 human breast cancer cells". Biochemical and Biophysical Research Communications294 (4): 785–90. doi:10.1016/S0006-291X(02)00554-5. PMID12061775.
Attie AD, Krauss RM, Gray-Keller MP, Brownlie A, Miyazaki M, Kastelein JJ, Lusis AJ, Stalenhoef AF, Stoehr JP, Hayden MR, Ntambi JM (Nov 2002). "Relationship between stearoyl-CoA desaturase activity and plasma triglycerides in human and mouse hypertriglyceridemia". Journal of Lipid Research43 (11): 1899–907. doi:10.1194/jlr.M200189-JLR200. PMID12401889.
Cohen P, Ntambi JM, Friedman JM (Dec 2003). "Stearoyl-CoA desaturase-1 and the metabolic syndrome". Current Drug Targets. Immune, Endocrine and Metabolic Disorders3 (4): 271–80. doi:10.2174/1568008033340117. PMID14683458.
Shiwaku K, Hashimoto M, Kitajima K, Nogi A, Anuurad E, Enkhmaa B, Kim JM, Kim IS, Lee SK, Oyunsuren T, Shido O, Yamane Y (May 2004). "Triglyceride levels are ethnic-specifically associated with an index of stearoyl-CoA desaturase activity and n-3 PUFA levels in Asians". Journal of Lipid Research45 (5): 914–22. doi:10.1194/jlr.M300483-JLR200. PMID14967817.
Wang Y, Kurdi-Haidar B, Oram JF (May 2004). "LXR-mediated activation of macrophage stearoyl-CoA desaturase generates unsaturated fatty acids that destabilize ABCA1". Journal of Lipid Research45 (5): 972–80. doi:10.1194/jlr.M400011-JLR200. PMID14967823.