With over seventy potassium channel genes in our genome and many implicated in pathophysiology, potassium channels and their multi-molecular complexes have taken centre stage in physiological and signaling research. Several of these genes, including those from the Shaker family i.e. Kv1.1, 1.2 and 1.4, have been cloned and their electrophysiological properties well characterized. Being one of the most well studied groups of proteins, these molecular marvels can selectively conduct potassium close to diffusion limits. Their concern however just does not end at aiding the remarkably regulated process of nerve conduction. Today, research into cell growth, division and signaling has opened avenues to explore the multi-faceted functions of these conduction pores. Over the years advancements in our understanding of potassium channel regulating proteins has convinced us of their multi-tier regulation strategy. It is not only the opening and closing of channels that is regulated, their surface densities are critically controlled for optimum cellular function. One such regulator, KCNRG (potassium channel regulator) is a potential tumour suppressor and our experiments with this protein in mammalian cells have implicated it to be an ER resident protein which tends to oligomerise. The lab has also succeeded in establishing that KCNRG produces no significant differences in the total levels of Kv proteins in a cell. Also, it does not affect generic cellular processes like endocytosis (clathrin dependent and independent) or exocytosis. However, further investigation with microscopy has revealed that it brings about a selective down-regulation of surface protein levels in the case of the Shaker family member Kv 1.4. In contrast, no such effect is observed in the Shab family member, Kv 2.1. KCNRG manages this process by interactive retention of the potassium channel in the endo-membrane of the cell i.e. ER. Such an interaction has been conclusively shown using cellular co-localization and immunoprecipitation. This association is speculated to be through the T1 domain of the Shaker family. Our work focuses on determining the details of this process and the mechanism this protein employs to bring about regulation of this family of potassium channels.
Life Sciences 2007 (2007) Proc Life Sciences, PC176
Poster Communications: Transporting a transporter – regulation of the Shaker family by the potassium channel regulator
H. Usman1, S. Kumari1, M. K. Mathew1
1. National Centre for Biological Sciences, Bangalore, India.
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