Module 3: Figure Ca2+ channel inactivation

Inactivation of P/Q-type channels.

In response to a maintained depolarization, the Ca2+ current inactivated almost completely in about 2 s. When Ca2+ was replaced by Ba2+, the current declined much more slowly, indicating that Ca2+ plays a role in inactivating the channels. The graph on the right illustrates how the degree of inactivation varies with the voltage of the test pulse, which provides further evidence to support a role for Ca2+ in inactivation. Reproduced by permission from Macmillan Publishers Ltd: Nature, DeMaria, C.D., Soong, T.W., Alseikhan, B.A., Alvania, R.S. and Yue, D.T. (2001) Calmodulin bifurcates the local Ca2+ signal that modulates P/Q-type Ca2+ channels. 411:484–489. Copyright (2001);; see Demaria et al. 2001.