(A and B) Representative data showing the SPR response of (A) NTF2 binding (red shaded area) and (B) blank PBS (blue shaded area) injections to Kapβ1-preloaded (green shaded area) Nsp1p-12FF brushes (black shaded area), respectively. For clarity, the black spikes correspond to BSA injections. In both cases, Kapβ1 binding to Nsp1p-12FF is long-lived with a considerable occupancy. In comparison, NTF2 binding to Nsp1p-12FF is short-lived with a far lower occupancy. (C) Corresponding height changes in a Kapβ1-preloaded Nsp1p-12FF layer after NTF2 injections (vertical dashed line). The layer transitions from a 40% extension at 15 μM Kapβ1 to a 20% extension in 270 μM NTF2. Note the similarity in layer height when blanks (i.e., PBS) are injected.