Figure 7.
Slob57 and Slob51 change the deactivation rate of dSlo. Deactivating tail currents following a 100-ms test pulse to +40 mV, with 110 μM free Ca2+, in the absence or presence of Slob57 or Slob51, were normalized and superimposed. The deactivation time constants for dSlo expressed alone, or together with Slob57 or Slob51, were obtained by fitting the tail currents with exponential functions. Both the current traces themselves and the exponential fits to the data (smooth lines) are shown in the figure. When dSlo is expressed without Slobs, in the voltage range from −20 to +40 mV, the tail currents can be fitted with a single exponential function with a mean, voltage-independent τ of 8.4 ± 0.5 ms. In the presence of Slob57 or Slob51, the tail currents can only be fitted, in the voltage range from +20 to +180 mV, with two voltage-independent exponential functions. Both the τf and the τs of dSlo in the presence of Slob57 or Slob51 are significantly different (P < 0.001) from the τ of dSlo expressed alone.