14 3 3th is a Binding Partner of Rat Eag1 Potassium Channels
The ether a go go (Eag) potassium (K+ channel belongs to the superfamily of voltage gated K+ channel. In mammals, the expression of Eag channels is neuron specific but their neurophysiological role remains obscure. We have applied the yeast two hybrid screening system to identify rat Eag1 (rEag1) interacting proteins from a rat brain cDNA library. One of the clones we identified was 14 3 3th, which belongs to a family of small acidic protein abundantly expressed in the brain. Data from in vitro yeast two hybrid and GST pull down assays suggested that the direct association with 14 3 3th was mediated by both the N and the C termini of rEag1. Co precipitation of the two proteins was confirmed in both heterologous HEK293T cells and native hippocampal neurons. Electrophysiological studies showed that over expression of 14 3 3th led to a sizable suppression of rEag1 K+ currents with no apparent alteration of the steady state voltage dependence and gating kinetics. Furthermore, co expression with 14 3 3th failed to affect the total protein level, membrane trafficking, and single channel conductance of rEag1, implying that 14 3 3th binding may render a fraction of the channel locked in a non conducting state. Together these data suggest that 14 3 3th is a binding partner of rEag1 and may modulate the functional expression of the K+ channel in neurons.
PloS one