A role for hydrophobic residues in the voltage-dependent gating of Shaker K+ channels.
A leucine heptad repeat is well conserved in voltage-dependent ion channels. Herein we examine the role of the repeat region in Shaker K+ channels through substitution of the leucines in the repeat and through coexpression of normal and truncated products. In contrast to leucine-zipper DNA-binding proteins, we find that the subunit assembly of Shaker does not depend on the leucine heptad repeat. Instead, we report that substitutions of the leucines in the repeat produce large effects on the observed voltage dependence of conductance voltage and prepulse inactivation curves. Our results suggest that the leucines mediate interactions that play an important role in the transduction of charge movement into channel opening and closing.
McCormack
K
K
Division of Biology 216-76, California Institute of Technology, Pasadena 91125.
Tanouye
M A
MA
Iverson
L E
LE
Lin
J W
JW
Ramaswami
M
M
McCormack
T
T
Campanelli
J T
JT
Mathew
M K
MK
Rudy
B
B
D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D004330:Drosophila / Q000235:genetics; D005260:Female; D006801:Humans; D015640:Ion Channel Gating; D007930:Leucine; D008564:Membrane Potentials; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009865:Oocytes / Q000502:physiology; D015221:Potassium Channels / Q000235:genetics* / Q000502:physiology; D011487:Protein Conformation; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic; D014981:Xenopus
D015221:Potassium Channels; D007930:Leucine