Atlante A, Passarella S, Minervini G M, Quagliariello E
Centro di Studio sui Mitocondri e Metabolismo Energetico, CNR, Bari, Italy.
Arch Biochem Biophys. 1994 Dec;315(2):369-81. doi: 10.1006/abbi.1994.1513.
Glutamine transport in both normal and acidotic rat kidney mitochondria was investigated using both isotopic techniques and by spectroscopic measurements in which glutamine metabolism was allowed to occur. Widely used criteria for demonstrating the occurrence of carrier-mediated transport were successfully applied in both cases. Three transport mechanisms were found to occur, namely glutamine uniport, active only during acidosis and glutamine/glutamate and glutamine/malate antiports, active in both normal and acidotic mitochondria. Efflux of glutamate, via a glutamate/OH- translocator, following glutamine uptake by mitochondria was experimentally ruled out. Glutamine uniport in acidotic mitochondria and glutamine/glutamate and glutamine/malate antiports in both normal and acidotic mitochondria were investigated in detail: differences found in Km and Vmax values, in pH and temperature dependence, and in the pattern of inhibitor sensitivity of glutamine transport demonstrated the existence of five different translocators whose activities were found to fit with the physiological requirements of renal ammoniogenesis.
利用同位素技术和光谱测量法，在正常和酸中毒大鼠肾线粒体中研究了谷氨酰胺转运，其中允许谷氨酰胺发生代谢。广泛用于证明载体介导转运发生的标准在这两种情况下均成功应用。发现存在三种转运机制，即谷氨酰胺单向转运，仅在酸中毒时活跃；谷氨酰胺/谷氨酸和谷氨酰胺/苹果酸反向转运，在正常和酸中毒线粒体中均活跃。通过实验排除了线粒体摄取谷氨酰胺后，谷氨酸通过谷氨酸/OH-转运体流出的情况。详细研究了酸中毒线粒体中的谷氨酰胺单向转运以及正常和酸中毒线粒体中的谷氨酰胺/谷氨酸和谷氨酰胺/苹果酸反向转运：在Km和Vmax值、pH和温度依赖性以及谷氨酰胺转运抑制剂敏感性模式方面发现的差异表明存在五种不同的转运体，其活性符合肾脏氨生成的生理需求。
