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The Journal of Neuroscience, August 15, 1999, 19(16):6865-6873
A Small Domain in the N Terminus of the Regulatory -Subunit
Kv2.3 Modulates Kv2.1 Potassium Channel Gating
María Dolores
Chiara,
Francisco
Monje,
Antonio
Castellano, and
José
López-Barneo
Departamento de Fisiología Médica y
Biofísica, Facultad de Medicina, Universidad de Sevilla,
E-41009 Sevilla, Spain
Recent work has demonstrated the existence of regulatory
K+ channel -subunits that are electrically silent
but capable of forming heterotetramers with other pore-forming subunits
to modify their function. We have investigated the molecular
determinant of the modulatory effects of Kv2.3, a silent
K+ channel -subunit specific of brain. This
subunit induces on Kv2.1 channels a marked deceleration of activation,
inactivation, and closing kinetics. We constructed chimeras of the
Kv2.1 and Kv2.3 proteins and analyzed the K+
currents resulting from the coexpression of the chimeras with Kv2.1.
The data indicate that a region of 59 amino acids in the N terminus,
adjacent to the first transmembrane segment, is the major structural
element responsible for the regulatory function of Kv2.3. The sequence
of this domain of Kv2.3 is highly divergent compared with the same
region in the other channels of the Kv2 family. Replacement of the
regulatory fragment of Kv2.3 by the equivalent of Kv2.1 leads to loss
of modulatory function, whereas gain of modulatory function is observed
when the Kv2.3 fragment is transferred to Kv2.1. Thus, this study
identifies a N-terminus domain involved in Kv2.1 channel gating and in
the modulation of this channel by a regulatory -subunit.
Key words:
molecular diversity; brain potassium channels; regulatory
-subunit; structure-function relationships; gating; modulation; heteromeric channels
Copyright © 1999 Society for Neuroscience 0270-6474/99/19166865-09$05.00/0
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