Table 5.

Distributions of amino acids inserted at stops in detected non-canonical peptides (columns Del, Swinger tri, Swinger tetra and Swinger penta), compared to the distribution of amino acids in canonical proteins encoded by the human mitogenome (Mito). Bias is the ratio between the frequency of the amino acid across all non-canonical peptides (column All) and its frequency in canonical proteins. P values are calculated using a chi-square test. Statistically significant results at P < 0.05 are underlined, and in bold when these are positive biases indicating greater than expected insertions at stop codons.

AA	Mito	Del	Swinger tri	Swinger tetra	Swinger penta	All peptides	Bias	P
A	225	1	10	7	1	19	0.65	0.062
C	22	3	3	3	0	9	3.15	0.002
D	66	2	5	10	0	17	1.98	0.010
E	88	5	9	4	2	20	1.75	0.020
F	216	3	2	4	1	10	0.36	0.0006
G	212	16	9	12	1	38	1.38	0.058
H	97	0	4	4	0	8	0.64	0.208
I,L	963	19	6	19	46	90	0.72	0.0006
K	95	18	22	22	11	73	5.92	4 × 10− 40
M	208	8	9	6	5	28	1.04	0.853
N	164	8	7	5	3	23	1.08	0.723
P	219	5	3	9	5	22	0.77	0.237
Q	90	18	7	8	10	43	3.68	2 × 10− 14
R	63	4	2	2	3	11	1.35	0.359
S	274	9	5	10	10	34	0.96	0.796
T	351	10	8	6	5	29	0.64	0.013
V	167	5	5	5	2	17	0.78	0.328
W	104	2	2	3	3	10	0.74	0.356
Y	135	2	1	7	4	14	0.80	0.414