The Fk1 domain of FKBP51 in complex with (2'R,5'S,12'R)-12'-cyclohexyl-2'-[2-(3,4-dimethoxyphenyl)ethyl]-3',19'-dioxa-10',13',16'-triazaspiro[cyclopropane-1,15'- tricyclo[18.3.1.0-5,10]tetracosane]-1'(24'),20',22'-triene-4',11',14',17'-tetrone