A sequence motif found in aDrosophilaheterochromatin protein is conserved in animals and plants

Open Access
Publisher Website
Google Scholar
Abstract
Modifiers of position-effect-variegation in Drosophila encode proteins that are thought to modify chromatin, rendering it heritably changed in its expressibiiity. In an attempt to identify similar modifier genes in other species we have utilized a known sequence homology, termed chromo box, between a suppressor of positioneffect- variegation, Heterochromatin protein 1 (HP1), and a repressor of homeotic genes, Polycomb (PC). A PCR generated probe encompassing the HP1 chrorno box was used to clone full-length murine cDNAs that contain conserved chrorno box motifs. Sequence comparisons, in situ hybridization experiments, and RNA Northern blot analysis suggest that the murine and human sequences presented in this report are homoiogues of the Drosophila HP1 gene. Chromo box sequences can also be detected in other animal species, and in plants, predicting a strongly conserved structural role for the peptide encoded by this sequence. We propose that epigenetic (yet heritable) changes in gene expressibility, characteristic of chromosomal imprinting phenomena, can largely be explained by the action of such modifier genes. The evolutionary conservation of the chromo box motif now enables the isolation and study of putative modifier genes in those animal and plant species where chromosomal imprinting has been described.