Table 2

Frequent octamers and their skew. The 24 most frequent octamers are ranked by frequency of occurrence on the leading strand (octamers with the same frequency of occurrence are ordered alphabetically). Frequent octamers that are reverse complements of frequent octamers are identified by their rank (in parentheses) beside that of their complement. All primary sequences are aligned by the CTG trimer. The average spacing for nonoverlapping sequences from this list is on the order of 1.3 kb. The percent skew is 100 × (f – f′)/(f + f′), wheref is the frequency of an octamer and f′that of its reverse complement.

Rank OctamerSkew (%) Count
1 (9)cgCTGgcg 15.6 867
2 (16)ggcgCTGg 19.6 826
3 (= Chi) gCTGgtgg 50.8761
4 (17) gCTGgcgg 13.1 719
5 (11)tgCTGgcg 9.4 719
6 gcgCTGgc 17.2 691
7tggcgCTG 15.4 677
8 (24) gCTGgcgc 12.6 659
10 cgCTGgtg 27.0 617
12 CTGgcggc 16.2589
13 CTGgcgca 13.2 575
14 gCTGgcga9.4 570
15 TGgcggcg 19.3 561
18 aaCTGgcg 12.5 543
19 gCTGgaag 11.0538
20 CTGgcgcg 15.4 524
21 gcgCTGga16.4 519
22 CTGgcgaa 14.9 515
23tgCTGgtg 29.1515