Abstract
Assembly of K channel subunits of the Shaker (Sh) family occurs in a subfamily specific manner. It has been suggested that subfamily specificity also applies in the association of subunits with Sh channels (Rhodes, K. J., Keilbaugh, S. A., Barrezueta, N. X., Lopez, K. L., and Trimmer, J. S. (1995) J. Neurosci. 15, 5360 –5371; Sewing, S., Roeper, J. and Pongs, O. (1996) Neuron 16, 455–463; Yu, W., Xu, J., and Li, M. (1996) Neuron 16, 441– 453). Here we show that the Drosophila subunit homologue Hyperkinetic (Hk) associates with members of the ether a` go-go (eag), as well as Sh, families. Anti-EAG antibody coprecipitates EAG and HK indicating a physical asso- ciation between proteins. Heterologously expressed Hk dramatically increases the amplitudes of eag currents and also affects gating and modulation by progesterone. Through their ability to interact with a range of sub- units, the subunits of voltage-gated K channels are likely to have a much broader impact on the signaling properties of neurons and muscle fibers than previously suggested.