Abstract: Expression vectors comprising a first nucleic acid sequence encoding a G protein coupled receptor (GPCR), wherein the GPCR encoded thereby is expressed as a fusion protein with a first detectable marker/signal, and a second nucleic acid sequence encoding a second polypeptide that is or comprises a second detectable marker/signal, wherein the second polypeptide is expressed as a fusion protein with a membrane localizing sequence are encompassed herein. The first nucleic acid sequence encoding the GPCR and the second nucleic acid sequence encoding the second polypeptide are under the transcriptional control of the same promoter and are operably linked via, for example, an internal ribosomal entry site (IRES). The first and second detectable markers, moreover, emit distinct detectable signals. Cells comprising these expression vectors are also encompassed herein, as are methods of using same to screen for G protein coupled receptor modulators.