Overlapping transcription units in the transient receptor potential locus of Drosophila melanogaster

We report the identification in Drosophila melanogaster of two mRNA transcripts that are derived from the transient receptor potential locus by transcription in opposite directions. The two transcripts overlap; one transcript has, as part of its 5'-untranslated sequence, the reverse complement of 442 bp of the 3' terminus of the transcript derived from the opposite DNA strand. Conceptual translation of the corresponding cDNA sequences predicted for one of the transcripts a polypeptide whose C terminus shares sequence and structural similarity with the cell-wall-binding domain of protein A from Staphylococcus aureus; for the transcript derived from the opposite DNA strand, a polypeptide of 264 amino acids was predicted, which showed no significant sequence homology with any known protein. The two transcripts have different tissue specificities: one is expressed predominantly in the eye and the other is in the body. These findings may have implications in the relationship between the organization of overlapping genes on opposite DNA strands and regulation of gene expression by antisense RNA.