Figure 5

Expression levels correlated between genes of U{1:1} pairs. Expression level correlation based on the number of transcripts (ESTs/cDNA) associated to U{1:1} gene pairs (A) and randomized nuclear gene pairs (B). Values were first normalized to take into account the size of the transcript resources in each species, the number of genes with a transcript and the total number of genes on each species, and then transformed by base 10 logarithm. We used only the gene pairs with a size difference between proteins equal to or smaller than 20 aa (526 U{1:1} and 8,390 randomized pairs). The green line represents the linear correlation for pairs of genes with at least 30 cognate transcripts (white area). U{1:1} genes pairs: r² = 0.51 and Kendall's test P-value = 1e-6; Random pairs sample: r² = 0.03 and Kendall's test P-value = 0.26. Diagonal lines delimit an expression similarity of 33% (light blue) and 50% (dark blue). (C) Percentage of similarity was recovered from ClustalW alignments of U{1:1} protein pairs encoded by highly (green, more than 30 cognate transcripts) and lowly (red, less than 30 cognate transcripts) transcribed genes.