UASt regulatory sequences are fused upstream of a genomic fragment that encodes the entire ple transcription unit. A frameshift mutation (single base insertion) has been introduced near the end of exon d (an exon that is specific to the non-neural isoform), along with a nearby compensatory mutation (single base deletion) at the beginning of exon e (an exon common to both neural and non-neural isoforms). In non-neural tissues, the expressed protein is expected to be active (it contains 15 missense amino acids in a non-critical region between the regulatory and catalytic domains but this region is not essential for enzyme activity), but in neural tissues, the single base deletion in exon e is expected to result in a truncated inactive protein.