Fig. 4.

Kinetics of Rab-LidA interactions. (A) ITC of 4 μM Rab1b∶GDP with 40 μM LidA_201–583. (B) Determination of the association rate constants (k_on) for Rab1b-LidA_201–583 interaction. The slope of a linear fit of the observed rate constants (k_obs) in dependence on the LidA_201–583 concentration gives k_on (see Table 1). The k_obs values have been obtained from fitting the change in fluorescence polarization upon shooting 1 μM Rab1b against increasing concentrations of LidA_201–583 to a single exponential. (C) Displacement of 0.2 μM Rab6a∶mGDP or Rab6a∶mGppNHp from LidA_201–583 by nonfluorescent Rab1b∶GppNHp (2 μM) monitored by fluorescence polarization (FP).