The present invention is directed to fusion proteins that can be used to assay gene transfer and expression both in vitro and in vivo. The fusion proteins contain a reporter protein, e.g. a somatostatin receptor, fused to a second protein, which may be a protein fusion tag. Alternatively, a fusion protein may be fused to a leader sequence. A leader sequence may localize an expressed protein, e.g localize a fusion protein to the cell membrane. The invention includes nucleic acids encoding the fusion proteins and methods of assaying for gene expression.