Compositional Features of Atypical Clusters 2A and 3A of E. coli Long (⩾500 Nucleotide) ORFs
| Clustering | A | B | C | |
| 2-means | no. of AT ORFs | 952 | 470 | 470 |
| no. of horizontally transferred genes in the overlap | 324 | 132 | 257 | |
| no. of class III genes in the overlap | 68 | 32 | 42 | |
| 3-means | no. of AT ORFs | 863 | 470 | 470 |
| no. of horizontally transferred genes in the overlap | 321 | 152 | 260 | |
| no. of class III genes in the overlap | 65 | 36 | 42 |
[i] Note that the number of horizontally transferred genes with a length ⩾ 500 nucleotides is 410 (Lawrence and Ochman 1998). The number of class III genes with a length ⩾ 500 nucleotides is 99 (Medigue et al. 1991).