RETARDED DIFFUSION OF ADP IN CARDIOMYOCYTES - POSSIBLE ROLE OF MITOCHONDRIAL OUTER-MEMBRANE AND CREATINE-KINASE IN CELLULAR-REGULATION OF OXIDATIVE-PHOSPHORYLATION
RETARDED DIFFUSION OF ADP IN CARDIOMYOCYTES - POSSIBLE ROLE OF MITOCHONDRIAL OUTER-MEMBRANE AND CREATINE-KINASE IN CELLULAR-REGULATION OF OXIDATIVE-PHOSPHORYLATION
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DOI：
10.1016/0005-2728(93)90166-d
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发表时间：
1993-09-13
期刊：
影响因子：
--
通讯作者：
PEROV, NA
中科院分区：
文献类型：
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作者：
SAKS, VA;VASILEVA, E;PEROV, NA
探讨了ADP胞内扩散受阻的可能原因。使用分离的带皮心脏纤维来研究外部添加的ADP控制线粒体呼吸的表观动力学参数。肌球蛋白-ATP酶参与细胞内ADP的结合，正如早先所设想的（Saks，V.A.，贝利科娃和Kuznetsov，A.V.（1991）Biochim. Biophys. Acta 1074，302-311）被完全排除，因为肌球蛋白剥夺的皮肤化的心脏纤维（“鬼”）显示出与完整的心脏纤维相同的动力学参数（ADP的K（m）app约为300 μ M）。对于线粒体外膜被破坏的纤维（25-35 μ M），获得了明显较低的表观K（m）值，这接近于对分离的心脏线粒体观察到的值。所获得的数据是在线粒体外膜的阴离子选择性低电导porine通道的ADP运动的限制。有人认为，这种膜的渗透性是由一些未知的细胞内因素控制的。在饱和浓度的肌酸（25 mM）的存在下，ADP的表观K（m）显着降低，由于肌酸激酶和氧化磷酸化反应在线粒体中的耦合。这种耦合是没有观察到的KCl介质中，其中线粒体肌酸激酶从膜脱离。它的结论是，在细胞内ADP细胞质和线粒体内空间之间的运动是由低电导率的阴离子通道外膜控制。因此，与腺嘌呤核苷酸移位酶偶联的线粒体肌酸激酶反应是体内控制氧化磷酸化的重要机制，因为它能够多种放大来自细胞质的这些非常弱的ADP信号。
Possible reasons for retarded intracellular diffusion of ADP were investigated. The isolated skinned cardiac fibers were used to study apparent kinetic parameters for externally added ADP in control of mitochondrial respiration. Participation of myosin-ATPase in binding of ADP within cells as it was supposed earlier (Saks, V.A., Belikova, Yu.O. and Kuznetsov, A.V. (1991) Biochim. Biophys. Acta 1074, 302-311) was completely excluded, since myosin-deprived skinned cardiac fibers ('ghosts') displayed the same kinetic parameters as intact ones (K(m)app for ADP about 300 muM). Significantly lower apparent K(m) values were obtained for fibers with osmotically disrupted outer mitochondrial membrane (25-35 muM), which was close to that observed for isolated heart mitochondria. The data obtained are in favor of limitation of ADP movement via anion-selective low-conductance porine channels in the outer membrane of mitochondria. It is proposed that the permeability of this membrane is controlled by some unknown intracellular factor(s). In the presence of saturating concentrations of creatine (25 mM) the apparent K(m) for ADP significantly decreases due to coupling of creatine kinase and oxidative phosphorylation reactions in mitochondria. This coupling is not observed in KCl medium in which mitochondrial creatine kinase is detached from the membrane. It is concluded that in the cells in-vivo ADP movement between cytoplasm and intramitochondrial space is controlled by low-conductivity anion channels in the outer membrane. Thus, the mitochondrial creatine kinase reaction coupled to the adenine nucleotide translocase is an important mechanism in control of oxidative phosphorylation in vivo due to its ability to manifold amplify these very weak ADP signals from cytoplasm.