Abstract: The disclosure relates to a plurality of cells, compositions and methods for identifying modulators of a target protein. The cells, compositions and methods comprise a (i) a target domain gene (ii) an intracellular chimeric G-protein alpha subunit comprising an endogenous G-protein alpha subunit with a humanized C-terminus; and (iii) an inducible reporter, wherein the expression of the reporter is dependent on the activation of the target domain encoded by target domain gene, and wherein the target domain gene comprises a barcode. The disclosure further relates to a host cell comprising a plurality of exogenous landing pads integrated in the host cell's genome, wherein each exogenous landing pad is integrated at a safe harbor genome loci in the host cell's genome.