DeRosa G, Swick R W
J Biol Chem. 1975 Oct 25;250(20):7961-7.
The distribution of alanine aminotransferase isozymes in several tissues from several species has been studied. In glycolytic tissues, such as skeletal and cardiac muscle, cytosolic alanine aminotransferase was the predominant form. In gluconeogenic tissues, such as liver and kidney, the concentration of the cytosolic alanine aminotransferase was much more variable; its presence, however, may be correlated with the presence of phosphoenolpyruvate carboxykinase in the same compartment. The particulate enzyme was found associated only with the matrix of the mitochondria. It was present only in those gluconeogenic tissues that can utilize alanine for glucose production, e.g. rat liver and pig liver and kidney; it was absent from rat kidney which cannot convert alanine to glucose. These observations, together with the kinetic parameters of the two isozymes, suggest that in vivo, mitochondrial alanine aminotransferase is involved in the conversion of alanine to pyruvate, while the cytosolic isoenzyme is mainly involved in the formation of alanine from pyruvate.
对几种物种的多个组织中丙氨酸转氨酶同工酶的分布进行了研究。在糖酵解组织，如骨骼肌和心肌中，胞质丙氨酸转氨酶是主要形式。在糖异生组织，如肝脏和肾脏中，胞质丙氨酸转氨酶的浓度变化更大；然而，它的存在可能与同一区室中磷酸烯醇式丙酮酸羧激酶的存在相关。颗粒酶仅在线粒体基质中发现。它仅存在于那些能够利用丙氨酸生成葡萄糖的糖异生组织中，例如大鼠肝脏、猪肝和猪肾；大鼠肾脏中不存在这种酶，因为大鼠肾脏不能将丙氨酸转化为葡萄糖。这些观察结果，连同两种同工酶的动力学参数，表明在体内，线粒体丙氨酸转氨酶参与丙氨酸向丙酮酸的转化，而胞质同工酶主要参与丙酮酸形成丙氨酸的过程。
