果蝇中的剂量补偿：NADP 酶活性与交叉反应物质
Dosage compensation in Drosophila: NADP-enzyme activities and cross-reacting material.
作者信息
Williamson J H, Bentley M M
出版信息
Genetics. 1983 Apr;103(4):649-58. doi: 10.1093/genetics/103.4.649.
The relationships between gene dosage, enzyme activities and CRM levels have been determined for G6PD and 6PGD. Enzyme activities and CRM levels were directly proportional and increased in genotypes carrying duplications of the respective structural genes. When a duplication consisting of the distal 45% of the X chromosome was used to duplicate Pgd+, 6PGD activity and CRM increased and G6PD activity decreased. When the proximal 55% of the X chromosome was duplicated, G6PD activity and CRM increased whereas 6PGD activity and CRM levels decreased. These observations support the model of dosage compensation of X-linked genes that invokes an autosomal activator in limited concentrations for which X-linked loci compete. The distal 45% of the X chromosome, when duplicated, caused a significant increase in NADP-malic enzyme activity and CRM levels, as if a structural gene for NADP-ME is sex-linked.
已确定了葡萄糖-6-磷酸脱氢酶（G6PD）和6-磷酸葡萄糖酸脱氢酶（6PGD）的基因剂量、酶活性与交叉反应物质（CRM）水平之间的关系。酶活性和CRM水平成正比，并且在携带各自结构基因重复的基因型中增加。当使用由X染色体远端45%组成的重复片段来重复Pgd+时，6PGD活性和CRM增加，而G6PD活性降低。当X染色体近端55%被重复时，G6PD活性和CRM增加，而6PGD活性和CRM水平降低。这些观察结果支持了X连锁基因剂量补偿模型，该模型认为存在一种浓度有限的常染色体激活剂，X连锁基因座会与之竞争。X染色体远端45%被重复时，会导致NADP-苹果酸酶活性和CRM水平显著增加，就好像NADP-ME的一个结构基因是性连锁的。
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