14-3-3[theta] is a Binding Partner of Rat Eag1 Potassium Channels

• Published in: PloS one 2012-07, Vol.7 (7), p.e41203
• Main Authors: Hsu, Po-Hao, Miaw, Shi-Chuen, Chuang, Chau-Ching, Chang, Pei-Yu, Fu, Ssu-Ju, Jow, Guey-Mei, Chiu, Mei-Miao, Jeng, Chung-Jiuan
• Format: Article
• Language: English
• Subjects: Brain; Genomic libraries; Neurons; Neurophysiology; Potassium channels; Proteins
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0041203

The ether-à-go-go (Eag) potassium (K.sup.+) channel belongs to the superfamily of voltage-gated K.sup.+ 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 14-3-3[theta], 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 14-3-3[theta] 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 14-3-3[theta] led to a sizable suppression of rEag1 K.sup.+ currents with no apparent alteration of the steady-state voltage dependence and gating kinetics. Furthermore, co-expression with 14-3-3[theta] failed to affect the total protein level, membrane trafficking, and single channel conductance of rEag1, implying that 14-3-3[theta] binding may render a fraction of the channel locked in a non-conducting state. Together these data suggest that 14-3-3[theta] is a binding partner of rEag1 and may modulate the functional expression of the K.sup.+ channel in neurons.