Ashmarina L I, Rusnak N, Miziorko H M, Mitchell G A
Service de Génétique Médicale, Hôpital Sainte-Justine, Montréal, Québec, Canada.
J Biol Chem. 1994 Dec 16;269(50):31929-32.
3-Hydroxy-3-methylglutaryl (HMG)-CoA metabolism is compartmentalized in mitochondria, endoplasmic reticulum, and peroxisomes. We investigated the subcellular distribution of HMG-CoA lyase (HL), which is found principally in mitochondria but in which we observed the potential peroxisomal targeting motif cysteine-lysine/arginine-leucine at the carboxyl terminus. We used differential and density gradient centrifugation to separate peroxisomes and mitochondria in liver homogenates of outbred CD-1 mice. Peroxisomal fractions contained 6.4% of total HL activity in mouse liver and 5.6% in human liver. Liver peroxisomal HL activity increased 2.3-2.5 times following induction of peroxisomal proliferation by clofibrate administration. Western blotting with anti-human HL antibodies confirmed the presence of immunoreactive HL in peroxisomal fractions. Mouse liver peroxisomal HL is distinct from mitochondrial HL, measuring approximately 2.5 kDa more by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. By fast protein liquid chromatofocusing analysis, the pI of peroxisomal HL is 7.3, in contrast to 6.2 for mitochondrial HL. These results are consistent with noncleavage of the mitochondrial leader peptide in peroxisomal HL. A distinct species of enzymatically active HL exists in peroxisomes and may play a role in HMG-CoA metabolism in that organelle.
3-羟基-3-甲基戊二酰辅酶A（HMG-CoA）代谢定位于线粒体、内质网和过氧化物酶体中。我们研究了HMG-CoA裂解酶（HL）的亚细胞分布，该酶主要存在于线粒体中，但我们在其羧基末端观察到潜在的过氧化物酶体靶向基序半胱氨酸-赖氨酸/精氨酸-亮氨酸。我们使用差速离心和密度梯度离心法分离远交群CD-1小鼠肝脏匀浆中的过氧化物酶体和线粒体。过氧化物酶体组分在小鼠肝脏中占总HL活性的6.4%，在人肝脏中占5.6%。用氯贝丁酯诱导过氧化物酶体增殖后，肝脏过氧化物酶体HL活性增加2.3至2.5倍。用抗人HL抗体进行蛋白质印迹证实过氧化物酶体组分中存在免疫反应性HL。小鼠肝脏过氧化物酶体HL与线粒体HL不同，通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳测量，其分子量约大2.5 kDa。通过快速蛋白质液相色谱聚焦分析，过氧化物酶体HL的pI为7.3，而线粒体HL的pI为6.2。这些结果与过氧化物酶体HL中线粒体前导肽未被切割一致。过氧化物酶体中存在一种独特的具有酶活性的HL，可能在该细胞器的HMG-CoA代谢中起作用。
