The transgenic construct contains a CMV enhancer/chicken beta-actin (CAG) promoter, a loxP-Stop-loxP (LSL) cassette containing a green fluorescent protein sequence (EGFP) and a polyadenylation signal, followed by the ER-BioID2(HA) coding sequence. ER-BioID2(HA) is composed of an IgK signal peptide, BioID2 coding sequence (containing a mutant biotin ligase (BirA*) sequence), a hemagglutinin (HA) tag, and the endoplasmic reticulum (ER) retention signal KDEL (Lys-Asp-Glu-Leu) tetrapeptide. (J:300755)