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The Journal of Neuroscience, December 15, 1999, 19(24):10706-10715

Xenopus Embryonic Spinal Neurons Express Potassium Channel Kv Subunits

Meredith A. Lazaroff, Alison D. Hofmann, and Angeles B. Ribera

Department of Physiology and Biophysics, University of Colorado Health Sciences Center, Denver, Colorado 80262

Developmental regulation of voltage-dependent delayed rectifier potassium current (I_Kv) of Xenopus primary spinal neurons regulates the waveform of the action potential. I_Kv undergoes a tripling in density and acceleration of it activation kinetics during the initial day of its appearance. Another voltage-dependent potassium current, the A current, is acquired during the subsequent day and contributes to further shortening of the impulse duration. To decipher the molecular mechanisms underlying this functional differentiation, we are identifying potassium channel genes expressed in the embryonic amphibian nervous system. Potassium channels consist of pore-forming () as well as auxiliary () subunits. Here, we report the primary sequence, developmental localization, and functional properties of two Xenopus Kv genes. On the basis of primary sequence, one of these (xKv2) is highly conserved with Kv2 genes identified in other species, whereas the other (xKv4) appears to identify a new member of the Kv family. Both are expressed in developing spinal neurons during the period of impulse maturation but in different neuronal populations. In a heterologous system, coexpression of xKv subunits modulates properties of potassium current that are developmentally regulated in the endogenous I_Kv. Consistent with xKv4's unique primary sequence, the repertoire of functional effects it has on coexpressed Kv1 subunits is novel. Taken together, the results implicate auxiliary subunits in regulation of potassium current function and action potential waveforms in subpopulations of embryonic primary spinal neurons.

Key words: potassium channels; Kv1 subunits; auxiliary Kv subunits; Xenopus embryos; electrical excitability; spinal cord neurons

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Copyright © 1999 Society for Neuroscience  0270-6474/99/192410706-10$05.00/0

This article has been cited by other articles:

				R. H. Pineda, C. S. Knoeckel, A. D. Taylor, A. Estrada-Bernal, and A. B. Ribera Kv1 Potassium Channel Complexes In Vivo Require Kv{beta}2 Subunits in Dorsal Spinal Neurons J Neurophysiol, October 1, 2008; 100(4): 2125 - 2136. [Abstract] [Full Text] [PDF]

				R. H. Pineda and A. B. Ribera Dorsal-Ventral Gradient for Neuronal Plasticity in the Embryonic Spinal Cord J. Neurosci., April 2, 2008; 28(14): 3824 - 3834. [Abstract] [Full Text] [PDF]

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