Table 4.

Comparison of the RNA editing frequencies at different codon positions with the C composition of codons in Arabidopsis mitochondrial genes shows that the frequency of editing sites does not reflect merely the distribution of Cs

Codon position	No. of editing sites at each codon position	Distribution of 441 editing sites in ORFs %	Distribution of the 6627 C residues in codons, %
First	154	34.9	33
Second	236	53.5	36.9
Third	51	11.6	30

The frequency of edited nucleotides is particularly higher in the second codon position and lower in the third.