Table 2.

List of 20 composition features, sorted in accordance to a decreasing z-value, showing a significant depletion in overlapping genes (z-value >4.41; two-tailed P = 10^-5; 319 degrees of freedom) with respect to non-overlapping genes.

Composition feature	Mean % content in overlapping genes (sd)	Mean % content in non-overlapping genes (sd)	Mean % difference between overlap and non-overlap	z-value
Tyr	2.2 (1.3)	3.6 (0.7)	-1.4	12.8
TA	3.6 (1.5)	5.3 (1.8)	-1.7	12.6
AT	5.7 (1.9)	7.1 (1.8)	-1.4	12.2
Amino acids with low codon degeneracy	36.9 (6.1)	41.2 (3.9)	-4.3	12.1
TAT(Tyr)	1.1 (0.9)	2.0 (0.8)	-0.9	11.7
T	21.6 (4.3)	25.3 (3.1)	-3.7	11.5
TTT(Phe)	1.3 (1.1)	2.3 (0.9)	-1.0	11.2
Val	5.1 (2.1)	6.5 (1.3)	-1.4	10.8
Phe	3.0 (1.7)	4.1 (0.8)	-1.1	10.6
TT	5.2 (2.3)	6.9 (1.8)	-1.7	10.4
TG	6.0 (1.8)	7.1 (1.1)	-1.1	10.4
ATT(Ile)	1.4 (1.1)	2.2 (0.8)	-0.8	10.4
Ile	4.3 (2.0)	5.6 (1.3)	-1.3	10.3
GTT(Val)	1.3 (1.0)	2.0 (0.8)	-0.7	10.2
AAT(Asn)	1.9 (1.3)	2.7 (1.1)	-0.8	10.0
GAT(Asp)	2.2 (1.5)	2.9 (1.1)	-0.7	8.7
Asp	4.2 (1.8)	5.1 (0.8)	-0.9	8.5
Asn	3.9 (1.6)	4.7 (1.2)	-0.8	8.3
GT	4.5 (1.5)	5.1 (1.0)	-0.6	7.8
AAA(Lys)	2.4 (1.7)	3.2 (1.4)	-0.8	7.6