This is the N-terminal domain of the beta chain found in Drosophila melanogaster protein BDBT (a FK506-Binding Protein) which stimulates the DBT circadian function. The domain contains the DBT-binding site. The domain is structurally homologous to the peptidyl prolyl isomerase (PPIase) regions of FK506-binding proteins despite low sequence homology. BDBT is structurally related to the immunophilin FKBP51 and it shares a common domain organization consisting of PPIase-like and TPR domains with noncanonical immunophilins such as FKBP38 or FKBPL [].
