THE ORIGIN AND DISTRIBUTION OF SHORT ORFS IN YEAST, E. coli AND B. subtilis GENOMES
酵母、大肠杆菌和枯草杆菌基因组中短ORF的分布与形成原因

Using the terminal codon method proposed by us, th e first kind of ORFs (denoted theoret-ical ORF) are predicted in yeast, Escherichia coli and Bacillus subtilis genomes. The theoretical ORF number and known ORF number verses its length are given. The two distribut ions are consistent with each other while ORF is length larger than 1 50 amino acids. There is a good linear relation between the logarithm of theoretical ORF numbers and its length for the theoretical ORF s horter than 150 amino acids. We suppose that the theoretical ORFs and their linear relation with the length of ORFs come from the randomne ss of the DNA sequences. The relation between ORF distribution and GC content, and be-tween ORF distribution and length for component-constr ained random sequences are analyzed. The results show that our supposi tion is correct. The ratio of the number of known ORF and short the oretical ORF are given. The relation may be useful for gene identific ation.