Insertion of helix linkers (A) SDS-PAGE of the probes inserted with helix linkers. Lane 1, FKBP/C; Lane 2, FKBP / 4 × DDAKK /C; Lane 3, FKBP/ 7 × DDAKK /C. (B) PCA using the probe with 4 × DDAKK. The probes (100 nM each) with/without equimolar rapamycin was used (n = 3). (C) PCA using the probe with 7 × DDAKK. The condition is the same as in (B).