Labate J, Eanes W F
Department of Ecology and Evolution, State University of New York, Stony Brook 11794.
Genetics. 1992 Nov;132(3):783-7. doi: 10.1093/genetics/132.3.783.
Demonstrating that naturally occurring enzyme polymorphisms significantly impact metabolic pathway flux is a fundamental step in examining the possible adaptive significance of such polymorphisms. In earlier studies of the glucose-6-phosphate dehydrogenase (G6PD) polymorphism in Drosophila melanogaster, we used two different methods, exploiting both genotype-dependent interactions with the 6Pgd locus, and conventional steady-state kinetics to examine activity differences between the two common allozymes. In this report we use 1-14C- and 6-14C-labeled glucose to estimate directly genotype-dependent flux differences through the pentose shunt. Our results show that G6pdA genotype possesses statistically lower pentose shunt flux than G6pdB at 25 degrees. We estimate this to be about a 32% reduction, which is consistent with the two former studies. These results reflect a significant responsiveness of pentose shunt flux to activity variation at the G6PD-catalyzed step, and predict that the G6PD allozymes generate a polymorphism for pentose shunt flux.
证明自然发生的酶多态性会显著影响代谢途径通量，是研究此类多态性可能的适应性意义的基本步骤。在早期对黑腹果蝇葡萄糖-6-磷酸脱氢酶（G6PD）多态性的研究中，我们使用了两种不同的方法，一种利用与6Pgd基因座的基因型依赖性相互作用，另一种利用传统的稳态动力学来检测两种常见同工酶之间的活性差异。在本报告中，我们使用1-14C和6-14C标记的葡萄糖直接估计通过戊糖支路的基因型依赖性通量差异。我们的结果表明，在25摄氏度时，G6pdA基因型的戊糖支路通量在统计学上低于G6pdB。我们估计这大约降低了32%，这与前两项研究一致。这些结果反映了戊糖支路通量对G6PD催化步骤活性变化的显著响应，并预测G6PD同工酶产生了戊糖支路通量的多态性。
