HSC70 directly binds to both folded and disordered CTA1.
A, HSC70 was perfused over a CTA1-coated SPR sensor at 15 or 37 °C. HSC70 was removed from the perfusion buffer 300 s after injection. B, five concentrations of HSC70 (1600, 800, 400, 200, and 100 ng/ml) were perfused over a CTA1-coated SPR sensor at 37 °C. HSC70 was removed from the perfusion buffer after 300 s. Best fit curves (orange lines) derived from five independent experiments with each protein concentration were calculated using a 1:1 Langmuir fit. A KD of 4.5 ± 3.6 nm was calculated from all five data sets, which produced an average ka of 6.2 × 105 ± 2.2 × 105
m−1 s−1 and a kd of 1.7 × 10−3 ± 0.7 × 10−3 s−1. Errors represent S.D.