Enhancer of rudimentary(p1), e(r)p1, a highly conserved enhancer of the rudimentary gene

P element tagging helps clone the enhancer of rudimentary e(r) gene of Drosophila melanogaster that maps to the 8B region on the X chromosome. The 1.0-kb transcript encoded by e(r) is found in males and females while the 1.2-kb transcript is seen more in females. The mutant e(r)P1 allele has these two transcripts at very low levels, and has the P element in the 5'-untranslated leader domain near the transcription initiation site. The P element acts through the transcription suppression or through polyadenylation and transcription termination signals.