Repeated, protein-encoding heterochromatic genes cause inactivation of a juxtaposed euchromatic gene.

Euchromatic genes are often silenced by rearrangements that place them within or near heterochromatin, a phenomenon known as position effect variegation (PEV). However, little is known about molecular structure of cis-acting heterochromatic fragments responsible for PEV. Here we report that heterochromatic cluster containing Stellate repeats, that encode putative regulatory subunit of protein kinase CK2 cause PEV of a reporter white 'mini-gene'. It is the first example of an euchromatic gene being silenced because of the proximity to the natural, well-defined heterochromatic repeat cluster.