Figure 3.

Sequence preferences around human insertions. Shown are profiles of log odds (base 2) for the nucleotide composition around human insertions of lengths 1-4. The 0.95 confidence intervals are plotted for each frequency. For each offset relative to the insertion point, we computed the frequency of each nucleotide and compared it to the frequency in genomic regions with similar GC content. The graphs indicate strong preferences for specific nucleotides in the context of an insertion, suggesting these nucleotides are contributing to the insertion process. The shaded region represents the nucleotide profile of the inserted sequence itself. Profiles around chimp insertions are highly similar to those shown here (Figure S3 in Additional data file 1). The number of events in flies is too small to reliably define these profiles.