Joshi Mandar, Jeoung Nam Ho, Popov Kirill M, Harris Robert A
Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202-5122, USA.
Biochem Biophys Res Commun. 2007 Apr 27;356(1):38-44. doi: 10.1016/j.bbrc.2007.02.108. Epub 2007 Feb 28.
A novel phosphatase has been cloned and partially characterized. It has a mitochondrial leader sequence and its amino acid sequence places it in the PP2C family like two known mitochondrial phosphatases. Western blot analysis of subcellular fractions and confocal microscopy of 3T3L1 preadipocytes expressing the GFP-tagged protein confirm its mitochondrial localization. Western blot analysis indicates that the protein is expressed in several mouse tissues, with highest expression in brain, heart, liver, and kidney. The recombinant protein exhibits Mn(2+)-dependent phosphoserine phosphatase activity against the branched-chain alpha-keto acid dehydrogenase complex, suggesting the enzyme may play a role in regulation of branched chain amino acid catabolism. Whether there are other mitochondrial substrates for the enzyme is not known.
一种新型磷酸酶已被克隆并进行了部分特性分析。它具有线粒体前导序列，其氨基酸序列使其与两种已知的线粒体磷酸酶一样，属于PP2C家族。对亚细胞组分的蛋白质印迹分析以及对表达绿色荧光蛋白标记蛋白的3T3L1前脂肪细胞进行共聚焦显微镜检查，证实了其线粒体定位。蛋白质印迹分析表明，该蛋白在几种小鼠组织中表达，在脑、心脏、肝脏和肾脏中表达最高。重组蛋白对支链α-酮酸脱氢酶复合体表现出依赖锰（2+）的磷酸丝氨酸磷酸酶活性，这表明该酶可能在支链氨基酸分解代谢的调节中发挥作用。该酶是否还有其他线粒体底物尚不清楚。
