There seem to be few if aspects of developmental biology affected by this gene, in contrast to the useful examples of genetic effects it provides. Zeste is a DNA binding protein, activating genes by binding to regulatory regions and forming multiprotein complexes. This property is termed transactivation. PEV will inactivate, in a capricious manner, a gene when the gene is placed near heterochromatin by chromosomal rearrangement. Heterochromatin is the genetically silent area of a chromosome, a quiet haven in what is otherwise a noisy workzone.
Variegation produces a quixotic expression of a gene, with the gene now turned on, now turned off.
Variation in expression is found from fly to fly, and even between different cells in the same fly. This on-off gene status is passed on from a cell to that cell's offspring. Zeste is a recessive enhancer of the PEV phenomena. Two genes subject to PEV are white and Notch . Pc-G mutants failing to inactivate transcription of genes usually subject to their gene silencing effects.