Histogram of the lengths of the (Q+N)-rich domains for budding yeast, fruit fly and human. The distribution of sequence lengths for the (Q+N)-rich domains are shown for budding yeast (top panel), fruit fly (middle panel) and human (bottom panel). The y-axis is the number of regions per bin, and the x-axis is for bins with labels x such that each bin contains all sequences with length x to x + 24 inclusive. The mean and median lengths for each of these distributions are as follows (organism, mean (± SD), median): budding yeast, 209 ± 209, 116; fruit fly, 236 ± 389, 89; human, 553 ± 730, 268. Only the distributions up to bin x = 275 are shown; a sizeable proportion of each distribution is longer than 275 residues (budding yeast 30% of sequences, fruit fly 22% and human 44%).