Shield-1 (Shld1) is a specific, cell-permeant and high-affinity ligand of FK506-binding protein-12 (FKBP), and reverses the instability by binding to mutated FKBP (mtFKBP), allowing conditional expression of mtFKBP-fused proteins. Shield-1 can stabilize proteins tagged with a mutated FKBP12-derived destabilization domain (DD)[2].In Vitro: Shield-1 (0.1 nM-1 μM) responses characterization of destabilizing domains.Shield-1 (1 μM; 24 h) treatment shows excellent expression on both TRPV5 and YFP when fused the mtFKBP destabilizing domain to either TRPV5 or YFP, and leads to mtFKBP-TRPV5 forming a functional ion channel[2].