The relationship between the inactivation rate and the number of fast subunits is exponential, indicating a cooperative mechanism where the C-type conformational change involves all four subunits.
C-type inactivation of potassium channels involves a cooperative conformational change requiring all four subunits.
C-type inactivation of potassium channels is distinct from N-terminal mediated (N-type) inactivation and involves a closing of the outer mouth of the channel. We have investigated the role of the individual subunits of the tetrameric channel in the C-type inactivation conformational change by comparing the inactivation rates of channels constructed from different combinations of subunits. The relationship between the inactivation rate and the number of fast subunits is exponential, as would be predicted by a cooperative mechanism where the C-type conformational change involves all four subunits, and rules out a mechanism where a conformational change in any of the individual subunits is sufficient for inactivation. Subunit interactions in C-type inactivation are further supported by an interaction between separate mutations affecting C-type inactivation when in either the same or separate subunits.
Ogielska et al. (1995) studied C-type inactivation of potassium channels. Different combinations of potassium channel subunits was evaluated on Inactivation rates of channels. The relationship between the inactivation rate and the number of fast subunits is exponential, indicating a cooperative mechanism where the C-type conformational change involves all four subunits.