P{HomingPigeon.FRT} is an enhancer trap construct that encodes a lacZ reporter. The enhancer trap sequence is at the 5' end of the element and consists of sequence including the weak P\T promoter and coding sequence for the first 125 P\T amino acids fused upstream of the lacZ coding sequence. Downstream of the enhancer trap sequence is an FRT cassette that contains a 6.7kb 'homing fragment' from the bithorax complex (from the region between the bxd and iab-2 regulatory regions) plus the ry^+t7.2 marker allele. The homing fragment causes the P{HomingPigeon.FRT} element to insert preferentially into or near the bithorax complex. It does not contain any known promoter, but acts as a boundary element.

The lacZ reporter encoded by the P{HomingPigeon.FRT} construct is expected to be localized to the nucleus, because it is fused to the N-terminal 125 amino acid residues of P\T (which have been shown to be sufficient for nuclear localization).