The Journal of Neuroscience, October 1, 1999, 19(19):8327-8336
The Inwardly Rectifying K+ Channel Subunit GIRK1
Rescues the GIRK2 weaver Phenotype
Ping
Hou,
Shuizhong
Yan,
Weijen
Tang, and
Deborah J.
Nelson
Department of Neurobiology, Pharmacology, and Physiology, The
University of Chicago, Chicago, Illinois 60637
The weaver (wv) gene has been
identified as a glycine to serine substitution at residue 156 in the H5
region of inwardly rectifying K+ channel, GIRK2. The
mutation is permissive for the expression of homotetrameric channels
that are nonselective for cations and G-protein-independent.
Coexpression of GIRK2wv with GIRK1, GIRK2, or GIRK3 in
Xenopus oocytes along with expression of subunit
combinations linked as dimers and tetramers was used to investigate the
effects of the pore mutation on channel selectivity and gating as a
function of relative subunit position and number within a
heterotetrameric complex. GIRK1 formed functional,
K+ selective channels with GIRK2 and GIRK3.
Coexpression of GIRK2wv with GIRK1 gave rise to a
component of K+-selective, G-protein-dependent
current. Currents resulting from coexpression of GIRK2wv
with GIRK2 or GIRK3 were weaver-like. Current from
dimers of GIRK1-GIRK2wv, GIRK2-GIRK2wv,
and GIRK3-GIRK2wv was phenotypically similar to that
obtained from coexpression of monomers. Linked tetramers containing
GIRK1 and GIRK2wv in an alternating array gave rise to
wild-type, K+-selective currents. When two mutant
subunits were arranged adjacently in a tetramer, currents were
weaver-like. These results support the hypothesis that
in specific channel stoichiometries, GIRK1 rescues the
weaver phenotype and suggests a basis for the selective neuronal vulnerability that is observed in the weaver mouse.
Key words:
K+ channels; weaver mice; G-proteins; Xenopus
oocytes; voltage clamp; neurons
Copyright © 1999 Society for Neuroscience 0270-6474/99/19198327-10$05.00/0