lexAop and UAS regulatory sequences and a minimal Hsp70 promoter (derived from the pUASTLOTattB vector) are fused upstream of a fusion protein that encodes an basolaterally localized nanobody-based GFP trap for intracellular proteins. The fusion protein contains the nrv1 coding sequence (from the LD02379 cDNA clone) with the GFP-binding VHH(GFP4) nanobody inserted near the N-terminal end (between the first and second exon) and a mCherry fluorescent tag inserted at the C-terminal end. The VHH(GFP4) nanobody faces the intracellular space. The lexAop and UAS regulatory sequences are flanked by loxP and lox2272 sites respectively (meaning that the P1cre recombinase can be used to excise one of the enhancers in a mutually exclusive manner if desired).