Wang Jian, Yu Lan, Schmidt Robert E, Su Chen, Huang Xiaodi, Gould Kenneth, Cao Guoqing
Cardiovascular Division, Lilly Research Labs, Eli Lilly and Company, DC 0343, Indianapolis, IN 46285, USA.
Biochem Biophys Res Commun. 2005 Jul 8;332(3):735-42. doi: 10.1016/j.bbrc.2005.05.013.
Stearoyl-CoA desaturase (SCD) is an integral membrane protein of the endoplasmic reticulum (ER) that catalyzes the formation of monounsaturated fatty acids from saturated fatty acids. Recent studies suggest that SCD is a key regulator of energy metabolism and has implications in dislipidemia and obesity. Four SCD isoforms (SCD1-4) have been identified in mouse. In human, only one SCD isoform has been characterized so far. Here we report that the previously reported human ACOD4 gene encodes a distinct stearoyl-CoA desaturase, hSCD5. GenBank database mining revealed orthologues of hSCD5 in the primates, but not in the rodents. In transiently transfected 293 cells, hSCD5 co-localized with calnexin on ER membrane. Microsome fractions prepared from hSCD1 and hSCD5 transfected cells displayed similar delta 9 desaturase activity. Quantitative real-time RT-PCR analysis suggested that hSCD5 was abundantly expressed in adult brain and pancreas. These data suggested that hSCD5 plays a role distinct from that of hSCD1 during development and in normal physiological conditions.
硬脂酰辅酶A去饱和酶（SCD）是内质网（ER）的一种整合膜蛋白，可催化饱和脂肪酸形成单不饱和脂肪酸。最近的研究表明，SCD是能量代谢的关键调节因子，与血脂异常和肥胖有关。在小鼠中已鉴定出四种SCD亚型（SCD1 - 4）。在人类中，迄今为止仅鉴定出一种SCD亚型。在此我们报告，先前报道的人类ACOD4基因编码一种独特的硬脂酰辅酶A去饱和酶，即hSCD5。GenBank数据库挖掘显示，hSCD5在灵长类动物中有直系同源物，但在啮齿动物中没有。在瞬时转染的293细胞中，hSCD与钙网蛋白在内质网膜上共定位。从转染了hSCD1和hSCD5的细胞中制备的微粒体组分显示出相似的Δ9去饱和酶活性。定量实时RT - PCR分析表明，hSCD5在成体脑和胰腺中大量表达。这些数据表明，在发育过程和正常生理条件下，hSCD5发挥着与hSCD1不同的作用。
