FK506-binding protein 12 F36V mutant fusion protein (FKBP12(F36V) fusion protein)

FKBP12(F36V) fusion protein is an engineered construct used extensively in chemical biology and synthetic biology research. It is based on the human FK506-binding protein 12 (FKBP12), a member of the immunophilin family, with a specific F36V point mutation that creates a binding cavity of approximately 90 cubic angstroms[1]. This single amino acid substitution (phenylalanine to valine at position 36) generates a complementary pocket that allows selective binding to synthetic ligands containing a structural "bump," such as Shield-1 and SLF' derivatives[7]. The F36V mutation provides remarkable selectivity, with engineered ligands binding approximately 1,000 to 1,600-fold more tightly to FKBP12(F36V) compared to wild-type FKBP12[5][7]. This high affinity (subnanomolar Kd) and specificity make FKBP12(F36V) an exceptionally useful tag for diverse applications in living cells and animal models. The fusion protein serves multiple research purposes. It can be genetically fused to proteins of interest for fluorescent labeling using dye-conjugated ligands like FL-SLF', enabling visualization at low expression levels with minimal background staining[2][5]. Modified versions incorporating the L106P mutation create destabilizing domains (DDs) that render fusion proteins unstable and subject to degradation unless stabilized by small molecules like Shield-1, allowing reversible control of protein levels[3][7]. More recently, heterobifunctional molecules called dTAGs have been developed that recruit E3 ubiquitin ligases (CRBN or VHL) to induce rapid, targeted degradation of FKBP12(F36V)-tagged proteins[9]. The system has been optimized through various modifications, including neutralization of charged surface residues to prevent electrostatic interference with fusion partner function, and removal of cryptic Cre-LoxP sites for compatibility with conditional gene expression systems[3]. FKBP12(F36V) fusions have been successfully applied to membrane proteins, cytoplasmic proteins, nuclear proteins, and enzymes across multiple cell types and even in zebrafish and mouse models, demonstrating broad versatility for manipulating protein function in a specific, rapid, reversible, and tunable manner[2][3][5].

Other names

FKBP12(F36V) fusionFKBP(F36V) fusion proteinF36V-FKBP fusionFKBP12 F36V-tagged proteinFKBPF36V-fusion protein

Ligand-dependent protein stabilization (with Shield-1); Targeted protein degradation via PROTAC mechanism (with dTAG molecules recruiting E3 ubiquitin ligases like VHL or CRBN); High-affinity binding-mediated fluorescent labeling; Chemical-induced dimerization for signaling activation