Potassium channels are key components for the electrical properties of excitable cells, and voltage-gated potassium channels (Kv) control neuronal excitability. The function of these tetrameric channels is known to depend on their amino acid sequences as well as posttranslational modifications. Defects in Kv channel function have been associated with epileptic and behavioral abnormalities, as well as episodic ataxia, hypokalemic myokymia, and sleep reduction. ? Kv1.1 and Kv1.2 not only form axonal Kv channels controlling action potential propagation-a physiological function whose importance is evident from mutant phenotypes in fly, mouse and man but also form somatodendritic Kv channels in certain central neurons, which exhibit potassium currents sensitive to Kv1.1- or Kv1.2-specific toxins. The long-term objective of this research plan is to determine the role of glycosylation in Kv1.1 and Kv1.2 channel expression, surface localization, and function in transiently transfected hippocampal neurons. The hypotheses that native glycosylation is important for their proper surface localization and function will be tested in transiently transfected central neurons. The first two specific aims of this proposal are to determine if glycosylation plays a role in neuronal surface expression and localization and electrophysiological properties of Kv1 channels.
This aim will be achieved by immunofluorescence and voltage-clamp recording of wild type and nonglycosylated mutants.
The third aim i s to observe glycosylation of locally translated Kv1.1 channels in isolated neuronal dendrites by a glycanlabeling methodology.
This aim entails establishment of a method for labeling of locally translated glycoproteins in isolated dendrites. More than half of all human proteins are likely glycosylated, though the role of these glycan moieties is not understood. In the central nervous system, potassium channels are important for electrical excitability, and these channels are glycosylated. This proposal will determine the role of glycosylation on proper cellular localization and functional properties of potassium channels, as well as develop a method to test an existing suggestion that glycosylation can occur in dendrites. ? ? ?
| Thayer, Desiree A; Jan, Lily Y (2010) Mechanisms of distribution and targeting of neuronal ion channels. Curr Opin Drug Discov Devel 13:559-67 |
