丙氨酸乙醛酸氨基转移酶的介绍和研究进展

Introduction and Research Progress of Alanine-Glyoxylate Aminotransferase

摘要: 丙氨酸乙醛酸氨基转移酶-AGT (alanine-glyoxylate aminotransferase)是在肝脏中表达的一种蛋白酶，作用是将乙醛酸转化为甘氨酸，防止乙醛酸被氧化为对生物体有害的草酸；而同时又能参加糖异生代谢，为动物提供能量。有研究表明，在哺乳动物中，AGT既能靶向线粒体又能靶向过氧化物酶体，其细胞器靶向的位置往往是和动物不同食性密切相关。在肉食动物中，AGT主要定位到线粒体；在植食动物中，AGT主要定位到过氧化物酶体；而在杂食动物中，AGT既能定位到线粒体又能定位到过氧化物酶体。在原发性高草酸尿症1型(primary hyperoxaluria type 1)病人中，因为AGT错误的靶向线粒体而导致人体过氧化物酶体中的乙醛酸不能有效降解，乙醛酸最终转变为对人体有害的草酸钙，所以AGT在动物中正确的细胞器靶向至关重要。本文将从AGT的结构与功能、乙醛酸代谢、AGT细胞器定位、研究进展和研究展望方面来叙述AGT。

Abstract: The alanine-glyoxylate aminotransferase (AGT) is a protease expressed in the liver and plays an important role in transforming glyoxylate to glycine in case it isoxidated to harmful oxalate. Meanwhile, the gluconeogenesis of AGT is also important to supply energy to animals. Some re-searches show that AGT can target to mitochondria or peroxisome in mammals, and the location of AGT in organelle is related to their diet type. Generally, in carnivorous mammals, AGT is mainly targeted to mitochondria, while in herbivores, AGT is mostly targeted to peroxisome, and AGT is targeted to mitochondria and peroxisome in omnivores. Mistargeting of AGT to mitochondria in humans can lead to primary hyperoxaluria type 1 (PH1) disease for glyoxylate in peroxisome that cannot be efficiently detoxified and is finally converted to harmful calcium oxalate, so that the right organelle’s location of AGT is critical to animals. This review will state the structure, function, glyoxylate metabolism, organelle’s location, research progress and research prospect of the AGT.