Yagil G
Department of Cell Biology, Weizmann Institute of Science, Rehovot, Israel.
Yeast. 1994 May;10(5):603-11. doi: 10.1002/yea.320100505.
The TRACTS program was employed to map the occurrence of base tracts composed of only two bases in Saccharomyces cerevisiae chromosome III. The observed frequencies were compared with those expected in random DNA. A vast excess of long base tracts of the three possible two-base combinations, namely, purine.pyrimidine (R.Y), keto.imino (K.M) and weak;strong (W;S, mainly A,T rich), was documented. The observed excess places yeast in the same category as other eukaryote and organelle genomes analysed. The excess of the two-base tracts was considerably larger in the 1/3 of the chromosome not coding for a protein, in particular proximal to coding initiation and termination sites, but was observed for coding regions as well. A functional role for the excessive tracts, possibly as unwinding centers of particular genes, is proposed. Multiple occurrence of long two-base tracts is offered as another diagnostic to determine whether an open reading frame (ORF), or an ORF subregion, is an actually translated gene region.
TRACTS程序被用于绘制酿酒酵母三号染色体中仅由两种碱基组成的碱基序列的分布图。将观察到的频率与随机DNA中预期的频率进行比较。记录了三种可能的双碱基组合（即嘌呤·嘧啶（R.Y）、酮基·亚氨基（K.M）和弱·强（W;S，主要富含A、T））的大量长碱基序列。观察到的过量情况表明酵母与其他已分析的真核生物和细胞器基因组属于同一类别。在不编码蛋白质的染色体的1/3区域，尤其是靠近编码起始和终止位点的区域，双碱基序列的过量情况要大得多，但在编码区域也观察到了这种情况。有人提出，过量的序列可能具有功能性作用，也许是作为特定基因的解旋中心。长双碱基序列的多次出现被作为另一种诊断方法，以确定一个开放阅读框（ORF）或一个ORF子区域是否为实际翻译的基因区域。
