Time- and voltage-dependent modulation of a kv1.4 channel by a
[beta] subunit (kv[beta]3) cloned from ferret ventricle.
Castellino, Robert C., Michael J. Morales, Harold C. Strauss, and
Randall L. Rasmusson.
Department of Cell Biology, Department of Pharmacology, Department
of Medicine, Duke University Medical Center, Box 3845 Durham, NC
27710, USA; Department of Biomedical Engineering, Room 136, School of
Engineering, Box 90281, Duke University, Durham, NC 27708, USA. Phone
(919)684-3962, Fax (919)681-5932
APStracts 2:0176H, 1995.
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, co-expressed 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.
Received 10 March 1995; accepted in final form 25 April 1995.
APS Manuscript Number H233-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 9 May 1995.