Time- and voltage-dependent modulation of a Kv1.4 channel by a beta-subunit (Kv beta 3) cloned from ferret ventricle.
In mammals, voltage-gated K+ channels can be made of complexes containing alpha-subunits similar to the Shaker K+ channel and smaller cytoplasmic beta-subunits. Recent studies have suggested that these ancillary beta-subunits can modulate K+ channel gating properties. We studied the effects of a K+ channel beta-subunit, Kv beta 3, coexpressed with a Kv1.4 alpha-subunit, FK1, on the time and voltage dependence of channel activation, inactivation, recovery from inactivation, and deactivation, using an oocyte expression system. Kv beta 3 was found to accelerate both the fast and the slow component of Kv1.4 inactivation. Kv beta 3 also altered the relative contributions of the two components of inactivation by increasing the contribution of the slow component to the inactivation process. Kv beta 3 slowed recovery from inactivation for Kv1.4, but not for a Kv1.4 deletion mutant lacking N-type inactivation. Finally, steady-state activation and the time course of Kv1.4 current activation were not strongly influenced by Kv beta 3; however, deactivation was slowed in the presence of Kv beta 3. This study suggests that Kv beta 3 alters channel states which follow activation.
Castellino
R C
RC
Department of Cell Biology, Duke University Medical Center, Durham 27710, USA.
Morales
M J
MJ
Strauss
H C
HC
Rasmusson
R L
RL
D000818:Animals; D003001:Cloning, Molecular; D004594:Electrophysiology; D005289:Ferrets; D006352:Heart Ventricles; D015640:Ion Channel Gating; D009206:Myocardium / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism; D015221:Potassium Channels / Q000737:chemistry* / Q000502:physiology*; D013997:Time Factors; D014982:Xenopus laevis
D015221:Potassium Channels