Biochemical techniques for the study of voltage-gated sodium channel auxiliary subunits

Voltage-gated sodium channels auxiliary subunits evolutionary emerged nearly 500 million years ago during the Cambrian explosion. These subunits alter one the most important ion channels to electrical signaling, the voltage-gated sodium channels support the propagation of electric impulses in animals. The mechanism for the auxiliary subunits effects on the channels is poorly understand, as is the stoichiometry between the auxiliary subunit and the channel. The focus of my thesis is to generate assays and to use these approaches to understand the interactions different types of voltage-gated channels and their auxiliary subunits. A biochemical approach was taken to identify novel interactions between the eukaryotic sodium channel auxiliary subunits and a prokaryotic voltage-gated sodium channel, a protein that diverged from the eukaryotic voltage-gated sodium channels billions of years ago. These interactions between the auxiliary subunits and channels were probed with chemical and photochemical crosslinkers in search of interaction surfaces and similarity to explain the mechanisms of interaction. The work in this thesis identified novel interactions between the voltage-gated sodium channel auxiliary subunits and voltage-gated channels that are distantly related to the voltage-gated sodium channels principally thought to be modulated by the auxiliary subunits. From this work a rudimentary concept can be theorized that the voltage-gated sodium channel β-subunits and not only β1 have a more primary role in electrophysiology by associating with multiple different types of ion channels.