The real life of pseudogenes
The real life of pseudogenes
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DOI：
10.1038/scientificamerican0806-48
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发表时间：
2006-08-01
影响因子：
3
通讯作者：
Zheng, Deyou
中科院分区：
文献类型：
--
作者：
Gerstein, Mark;Zheng, Deyou
“假”基因看起来像真基因，但没有明显的功能，在20世纪70年代末首次被识别并被称为假基因，当时早期的基因猎人开始试图确定与重要分子产生相关的染色体位置。例如，在寻找制造贝塔格球蛋白的基因时，科学家发现了一个看起来像珠蛋白基因，但不可能产生蛋白质的DNA序列。贝塔球蛋白是一种通过血液输送氧气的血红蛋白的关键成分。基因解剖的基本功能部分因突变而失效，这使得细胞机器无法将基因转化为有用的分子。直到最近完成了涵盖人类和其他生物全基因组的测序项目，遗传学家才得以从空中俯瞰基因组图景，并体会到这样的奇特之处是多么地千篇一律。人类基因组由30多亿对核苷酸组成，这些核苷酸是DNA分子的组成部分。然而，只有不到2%的基因组DNA直接编码蛋白质。也许第三种是基因内的非编码序列，称为内含子。基因之间的剩余区域构成了我们DNA的绝大部分，其中大部分实际上是基因组暗物质，其功能在很大程度上仍然是一个谜。正是在这些看似贫瘠的土地上，大多数伪基因就像锈迹斑斑的汽车零件一样随机散落在大地上--数量惊人。
“FALSE” GENES, which look like real genes but have no apparent function, were first recognized and dubbed pseudogenes during the late 1970s, when early gene hunters began trying to pinpoint the chromosomal locations associated with production of important molecules. For example, while seeking the gene responsible for making betaglobin, a key component of the hemoglobin protein that transports oxygen through the bloodstream, scientists identified a DNA sequence that looked like a globin gene but could not possibly give rise to a protein. Essential functional parts of the gene’s anatomy were disabled by mutations, making it impossible for cellular machinery to translate the gene into a useful molecule.Only the far more recent completion of sequencing projects covering the full genomes of humans and other organisms allowed geneticists to get an aerial view of the genomic landscape and to appreciate how riddled with such oddities it is. The human genome is made up of more than three billion pairs of nucleotides, the building blocks of DNA molecules. Yet less than 2 percent of our genomic DNA directly encodes proteins. Perhaps a third is noncoding sequences within genes, called introns. The remaining tracts between genes constitute the great majority of our DNA, and much of it is effectively genomic dark matter whose function is still largely a mystery. It is in these seemingly barren expanses that most pseudogenes are randomly scattered like rusted car parts on the landscape—and in surprising numbers.