Echtay K S, Liu Q, Caskey T, Winkler E, Frischmuth K, Bienengräber M, Klingenberg M
Institute for Physical Biochemistry, University of Munich, Germany.
FEBS Lett. 1999 Apr 30;450(1-2):8-12. doi: 10.1016/s0014-5793(99)00460-3.
UCP3 is an isoform of UCP1, expressed primarily in skeletal muscle. Functional properties of UCP3 are still largely unknown. Here, we report about the expression of UCP3 and of UCP1 in inclusion bodies of Escherichia coli. On solubilization and reconstitution into proteoliposomes, both UCP3 and UCP1 transport Cl- at rates equal to the reconstituted native UCP1. Cl- transport is inhibited by low concentrations of ATP, ADP, GTP and GDP. However, no H+ transport activity is found possibly due to the lack of a cofactor presents in UCP from mitochondria. The specificity of inhibition by nucleoside tri- and diphosphate is different between UCP1 and UCP3. UCP1 is more sensitive to tri- than diphosphate whereas in UCP3, the gradient is reverse. These results show a new paradigm for the regulation of thermogenesis at various tissues by the ATP/ADP ratio. In brown adipose tissue, the thermogenesis is correlated with a low ATP/ADP whereas in skeletal muscle, non-shivering thermogenesis is active at a high ATP/ADP ratio, i.e. in the resting state.
解偶联蛋白3（UCP3）是解偶联蛋白1（UCP1）的一种同工型，主要在骨骼肌中表达。UCP3的功能特性在很大程度上仍不为人知。在此，我们报道了UCP3和UCP1在大肠杆菌包涵体中的表达情况。在溶解并重新组装到蛋白脂质体后，UCP3和UCP1均以与重新组装的天然UCP1相同的速率转运氯离子（Cl-）。低浓度的ATP、ADP、GTP和GDP可抑制Cl-的转运。然而，可能由于缺乏线粒体UCP中存在的辅因子，未发现质子（H+）转运活性。核苷三磷酸和二磷酸的抑制特异性在UCP1和UCP3之间有所不同。UCP1对三磷酸的敏感性高于二磷酸，而在UCP3中，这种梯度则相反。这些结果展示了一种通过ATP/ADP比值调控不同组织产热的新范例。在棕色脂肪组织中，产热与低ATP/ADP比值相关，而在骨骼肌中，非寒战产热在高ATP/ADP比值时活跃，即在静息状态下。
