Creating a Unified Framework for N-type Inactivation
In this Project we will test a specific hypothesis that we have developed to explain previously confounding aspects of voltage-gated potassium channel N-type inactivation gating. Our hypothesis is that what is traditionally termed the inactivated state is actually a compound state not a single state (called the “B” state). Furthermore, one of the two substates of B is in fact conductive and capable of closing like a normal open state.
Therefore we predict that under some experimental conditions, a subconductance state should be evident that has all the classically predicted properties of an inactivated state, except for being conductive. Importantly, we predict that the previous single channel studies on N-type inactivation would not see this subconductance, rather it only becomes prominent when the inactivation ball peptide has been modified in a specific manner. To test this model we will perform biophysical whole cell and single channel recordings on cells expressing wild type and N-type inactivation mutant channels.
Specific Aim 1: Single channel recording of the conductive B state.
Specific Aim 2: Single channel analysis of tail currents.
Specific Aim 3: Noise analysis of the B state.
Relevance of the project to IDDRC mission:
Inactivation of potassium channels is an important associative signal in the brain and therefore a critical process to understand if we are to develop molecular level insights into the brain processes that produce learning and memory. In this study we will test a novel hypothesis on N-type inactivation that seeks to provide a uniform framework to understand the molecular events occurring during inactivation and recovery.