Tanida Isei, Tanida-Miyake Emiko, Nishitani Tomohito, Komatsu Masaaki, Yamazaki Harumi, Ueno Takashi, Kominami Eiki
Department of Biochemistry, Juntendo University School of Medicine, Tokyo 113-8421, Japan.
Biochem Biophys Res Commun. 2002 Mar 22;292(1):256-62. doi: 10.1006/bbrc.2002.6645.
Apg7p is a unique E1 enzyme which is essential for both the Apg12p- and Apg8p-modification systems, and plays indispensable roles in yeast autophagy. A cDNA encoding murine Apg7p homolog (mApg7p) was isolated from a mouse brain cDNA library. The predicted amino acid sequence of the clone shows a significant homology to human Apg7p and yeast Apg7p. Murine Apg12p as well as the three mammalian Apg8p homologs co-immunoprecipitate with mApg7p. Site-directed mutagenesis revealed that an active-site cysteine within mApg7p is Cys(567), indicating that mApg7p is an authentic E1 enzyme for murine Apg12p and mammalian Apg8p homologs. The mutagenesis study also revealed that Apg12p has a substrate preference for mApg7p over the three Apg8p homologs, suggesting that the Apg12p conjugation by Apg7p occurs preferentially in mammalian cells compared with the modification of the three Apg8p homologs. We also report here on the ubiquitous expression of human APG7 mRNA in human adult and fetal tissues and of rat Apg7p in adult tissues.
Apg7p是一种独特的E1酶，对Apg12p和Apg8p修饰系统均至关重要，且在酵母自噬中发挥不可或缺的作用。从小鼠脑cDNA文库中分离出编码鼠Apg7p同源物（mApg7p）的cDNA。该克隆预测的氨基酸序列与人类Apg7p和酵母Apg7p具有显著同源性。鼠Apg12p以及三种哺乳动物Apg8p同源物与mApg7p共免疫沉淀。定点诱变显示，mApg7p内的活性位点半胱氨酸为Cys(567)，这表明mApg7p是鼠Apg12p和哺乳动物Apg8p同源物的真正E1酶。诱变研究还表明，与三种Apg8p同源物相比，Apg12p对mApg7p具有底物偏好性，这表明与三种Apg8p同源物的修饰相比，Apg7p介导的Apg12p缀合在哺乳动物细胞中优先发生。我们在此还报告了人类APG7 mRNA在成人和胎儿组织中的普遍表达以及大鼠Apg7p在成年组织中的表达。
