Degradation of stearoyl coenzyme A desaturase: Endoproteolytic cleavage by an integral membrane protease
Degradation of stearoyl coenzyme A desaturase: Endoproteolytic cleavage by an integral membrane protease
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DOI：
10.1091/mbc.9.12.3445
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发表时间：
1998-12-01
影响因子：
3.3
通讯作者：
Ozols, J
中科院分区：
文献类型：
--
作者：
Heinemann, FS;Ozols, J
硬脂酰辅酶A去饱和酶（SCD）是膜流动性的关键调节因子，翻转迅速，代表了内质网驻留蛋白的选择性降解原型。使用洗涤剂溶解，去饱和酶诱导的大鼠肝微粒体，我们的特点是降解SCD的蛋白酶。SCD的体外降解具有高度选择性，半衰期为3-4 h，并产生20 kDa的SCD C-末端片段。20-kDa片段的N末端被鉴定为Phe（177）。切割位点发生在SCD的保守的12个残基的疏水区段中，两侧是碱性残基簇。SCD蛋白酶仍然与微粒体膜后，外周和内腔蛋白已被选择性地删除。SCD蛋白酶存在于正常大鼠肝微粒体中并切割纯化的SCD。我们的结论是，SCD的快速营业额涉及一个组成性的微粒体蛋白酶的一个完整的膜蛋白的属性。
Stearoyl-coenzyme A desaturase (SCD) is a key regulator of membrane fluidity, turns over rapidly, and represents a prototype for selective degradation of resident proteins of the endoplasmic reticulum. Using detergent-solubilized, desaturase-induced rat liver microsomes we have characterized a protease that degrades SCD. Degradation of SCD in vitro is highly selective, has a half-life of 3-4 h, and generates a 20-kDa C-terminal fragment of SCD. The N terminus of the 20-kDa fragment was identified as Phe(177). The cleavage site occurs in a conserved 12-residue hydrophobic segment of SCD flanked by clusters of basic residues. The SCD protease remains associated with microsomal membranes after peripheral and lumenal proteins have been selectively removed. SCD protease is present in normal rat liver microsomes and cleaves purified SCD. We conclude that rapid turnover of SCD involves a constitutive microsomal protease with properties of an integral membrane protein.