THE ENHANCER OF POSITION-EFFECT VARIEGATION OF DROSOPHILA, E(VAR)3-93D, CODES FOR A CHROMATIN PROTEIN CONTAINING A CONSERVED DOMAIN COMMON TO SEVERAL TRANSCRIPTIONAL REGULATORS

In Drosophila modifying mutations of position-effect variegation have been successfully used to genetically dissect chromatin components. Th e enhancer of position-effect variegation E(var)3-93D [formerly E-var( 3)3] encodes proteins containing a domain common to the transcriptiona l regulators tramtrack and the products of the Broad complex. It inter acts with a number of chromatin genes that suppress position-effect va riegation. Mutations in E(var)3-93D exhibit an imprinting-like effect on the Y chromosome. This effect is transmitted paternally over severa l generations. Homeotic transformations in E(var)3-93D mutants indicat e an involvement of the gene products in regulation of homeotic gene c omplexes. An antiserum raised against E(var)3-93D protein detects this chromosomal protein in a large subset of sites in polytene chromosome s. Our genetic and molecular data suggest that the proteins of E(var)3 -93D are generally involved in establishing and/or maintaining an open chromatin conformation.