The long-term objective of this application is to develop an understanding of the effects of glycosylation on the expression and function of voltage-gated ion channels. The voltage-gated Kv1.2 potassium (K+) channel is expressed in a cell system and used as a model ion channel to investigate the effects of glycosylation on its gating. Work to date suggests that removing the sugar tree from the S1-S2 linker alters gating- activation kinetics are slowed and there is a positively shifted V1/2 and a shallower G-V slope relation. Both the bulky sugar tree on the channel as well as some of the negatively charged sialic acids on the tree appears to be responsible for the functional changes. It is hypothesized that increasing or decreasing the glycosylation state of Kv1.2, as well as changing the position of a sugar tree on an extracellular linker, may have varying effects on channel gating as well as dictating the gating parameters affected. Using mutagenesis, biochemical, and electrophysiological techniques the above hypothesis will be tested. The application seeks to determine general principles governing the effect of glycosylation on ion channel gating. Because some ion channels are differentially glycosylated, the work also suggest that neurons could use the glycosylation degree of an ion channel to increase channel function diversity and increase signaling characteristics of excitable cells. A number of disorders also appear to be due to changes in ion channel function and thus the work may also have clinical relevance.
