Binding behaviors of FcBP-Encapsulin to antibodies. (A) QCM resonance frequency change (-ΔF) profiles of either encapsulin (dashed line) or FcBP-encapsulin (solid line) on the gold QCM sensors and subsequent deposition of rabbit IgG on the monolayer of FcBP-encapsulin. Filled and open arrows indicate the timing of encapsulin variant and rabbit IgG introductions, respectively. Thin arrows indicate the timing of buffer washing. SPR analyses of FcBP-encapsulin (B) and encapsulin (C) bindings to rabbit IgG immobilized gold SPR sensors. Filled and open arrows indicate the timing of encapsulin variant introductions and buffer washing, respectively. Inset of (C) is amplified graph of low RU ranges.