Figure 6.

A graphical summary of the requirements for HP1 recombination. The recombination protein-binding sites in the HP1 attachment sites are shown, and the requirements for either integration (top) or excision (bottom) are shown. Percentages represent the amount of activity obtained in experiments using substrates mutated at the given site. The percentage indicated for IBS6 represents the complete deletion of both half-sites; the percentage of activity remaining when IBS6b alone was deleted is shown in parentheses. Circles schematically represent the strength of the requirement for bound protein at a given site. Black circles represent a completely required site while gray circles signify sites which stimulate recombination. Open circles represent sites which when mutated still produce levels of activity >80% of wild-type; these are identified as dispensable sites. Open squares represent sites which when bound by protein are inhibitory to recombination.