Wilson J E
Department of Biochemistry, Michigan State University, East Lansing 48824-1319, USA.
J Bioenerg Biomembr. 1997 Feb;29(1):97-102. doi: 10.1023/a:1022472124746.
Binding of the Type I isozyme of mammalian hexokinase to mitochondria is mediated by the porin present in the outer mitochondrial membrane. Type I hexokinase from rat brain is avidly bound by rat liver mitochondria while, under the same conditions, there is no significant binding to mitochondria from S. cerevisiae. Previously published work demonstrates the lack of significant interaction of yeast hexokinase with mitochondria from either liver or yeast. Thus, structural features required for the interaction of porin and hexokinase must have emerged during evolution of the mammalian forms of these proteins. If these structural features serve no functional role other than facilitating this interaction of hexokinase with mitochondria, it seems likely that they evolved in synchrony since operation of selective pressures on the hexokinase-mitochondrial interaction would require the simultaneous presence of hexokinase and porin capable of at least minimal interaction, and be responsive to changes in either partner that affected this interaction. Recent studies have indicated that a second type of binding site, which may or may not involve porin, is present on mammalian mitochondria. There are also reports of hexokinase binding to mitochondria in plant tissues, but the nature of the binding site remains undefined.
哺乳动物己糖激酶I型同工酶与线粒体的结合是由线粒体外膜中的孔蛋白介导的。大鼠脑I型己糖激酶能与大鼠肝线粒体紧密结合，而在相同条件下，与酿酒酵母的线粒体无明显结合。先前发表的研究表明，酵母己糖激酶与肝或酵母的线粒体之间缺乏显著相互作用。因此，孔蛋白和己糖激酶相互作用所需的结构特征一定是在这些蛋白质的哺乳动物形式进化过程中出现的。如果这些结构特征除了促进己糖激酶与线粒体的这种相互作用外没有其他功能作用，那么它们似乎是同步进化的，因为对己糖激酶-线粒体相互作用施加选择压力需要同时存在能够至少进行最小相互作用的己糖激酶和孔蛋白，并对影响这种相互作用的任何一方的变化做出反应。最近的研究表明，哺乳动物线粒体上存在第二种结合位点，该位点可能涉及也可能不涉及孔蛋白。也有报道称己糖激酶能与植物组织中的线粒体结合，但结合位点的性质尚不清楚。
