Schematic depiction of the expression vector for the BAP-based receptor as well as the corresponding biotin ligase. Shown are the CMV promoter element, the signal peptide (depending on the construct being the EGFR signal peptide, the Igκ signal peptide or the BM40 signal peptide, the latter two furthermore possessing an elongated 5’ UTR), the biotin acceptor peptide, a nanoluciferase, an epitope tag for A3C5 antibodies, the EGFR N-terminal transmembrane α-helix, mRuby, a Strep-tag II, an IRES from eIF4G1 for polycistronic transcription, BirA including a Igκ signal peptide as well as an ER retention signal sequence, and the hGH polyadenylation signal sequence.