299bp of genomic sequence from immediately upstream of the predicted start codon of Ir75b is fused upstream of a membrane-targeted fusion protein containing the Tag:SS(Akh) signal peptide, the Hsap\CD4 transmembrane domain, a tandem fluorescent dimer composed of EGFP and GFP and an endoplasmic reticulum export signal from the Hsap\KCNJ2 gene.