Fig. 4. Concentration-dependence for acceleration of inactivation by the nanobody.

A Kv1.3 current traces elicited by depolarization to +50 mV in 2 mM K⁺ in the absence or presence of the NB. Holding voltage was −80 mV, tail voltage was −50 mV, current scale bars are 1 μA and red dotted line is zero current. Control trace and 100 nM NB are from one cell, and traces for other NB concentrations are from three different cells. Orange lines are fits of mono- (100 nM and 1 µM) or double exponential (control, 1 nM and 10 nM) functions (see Methods). B Influence of the NB on inactivation. Mean values for τ_slow and τ_fast are shown for control (filled black squares; n = 5;), 1 nM NB (right facing light orange triangles; n = 3) or 10 nM NB (filled upright pink triangles; n = 3). Mean values of τ are shown for 100 nM NB (filled orange circles; n = 5) and for 1 µM NB (filled dark red diamonds; n = 3). Open symbols denote individual experiments. Error bars are S.E.M. C Onset of inhibition by NB in 2 mM K⁺ solutions. Peak currents elicited by 500 ms steps from −80 to +40 mV were normalized to the maximum value in control. Addition of NB (orange bar) at 10 nM (triangles) or 100 nM (circles). Black lines are fits of a single exponential function to the data (see Methods). D Recovery from inhibition by the NB in 2 mM K⁺ solutions. Same voltage protocol as C with removal of the NB indicated by white bar (10 nM NB triangles and 100 nM circles). Currents were scaled by setting the initial values in NB to zero and normalizing to the maximum before the addition of the NB. Pulses delivered every 10 s but shown every 30 s for clarity. Black lines are fits of a sigmoidal function to the data (see Methods). E Concentration dependence for onset (τ_on) and recovery (τ_off) for NB. Mean values (filled symbols) for τ_on (n = 6 for 10 nM and 7 for 100 nM), τ_off and σ (n = 6), individual values (open symbols) from experiments like those in C, D. Error bars are S.E.M. Source data are provided as a Source Data file.