Ca 2+ ‐binding protein centrin 4 is a novel binding partner of rat Eag1 K + channels

Eag1 is neuron‐specific K + channel abundantly expressed in the brain and retina. Subcellular localization and physiological analyses in neurons reveal that Eag1 may participate in Ca 2+ ‐signaling processes in the synapse. Here, we searched for rat Eag1 (rEag1)‐binding proteins that may contribute to Ca 2+ regulation of the K + channel. Yeast two‐hybrid screening identified centrin 4, a member of the centrin family of Ca 2+ ‐binding proteins. GST pull‐down and immunoprecipitation assays in brain and retina lysates confirm the interaction of centrin with rEag1 in neurons. Centrin 4 binds to rEag1 in the absence of Ca 2+ . Raising Ca 2+ concentration enhances the association efficiency of centrin 4 and rEag1, and is required for the suppression of rEag1 currents by centrin 4. Altogether, our data suggest that centrin 4 is a novel binding partner that may contribute to Ca 2+ regulation of rEag1 in neurons.