Tubulin as a binding partner of the heag2 voltage-gated potassium channel.

The aim of this work was to investigate interactions of the human ether-a-go-go channel heag2 with human brain proteins. For this, we used heag2-GST fusion proteins in pull-down assays with brain proteins and mass spectrometry, as well as coimmunoprecipitation. We identified tubulin and heat shock 70 proteins as binding to intracellular C-terminal regions of the channel. To study functional effects, heag2 channels were expressed in Xenopus laevis oocytes for two-electrode voltage clamping. Coexpression of alpha-tubulin or the application of colchicine significantly prolonged channel activation times. Application at different times of colchicine gave similar results. The data suggest that colchicine application and tubulin expression do not affect heag2 trafficking and that tubulin may associate with the channel to cause functional effects. Coexpression of heat shock 70 proteins had no functional effect on the channel. The role of tubulin in the cell cytoskeleton suggests a link for the heag2 channel in tubulin-dependent physiological functions, such as cellular proliferation.