Required for underreplication of DNA, which is found in many late replicating euchromatic regions of salivary gland polytene chromosomes. Controls chromatin organization in polytene chromosomes (By similarity). Binds to polytene chromosomes from salivary glands. Localized at late-replicating intercalary heterochromatin and pericentric heterochromatin. Colocalizes with many Polycomb Group proteins binding sites on polytene chromosomes (By similarity).