A novel subunit for shal K+ channels radically alters activation and inactivation.
Shal (Kv4) potassium channel genes encode classical subthreshold A-currents, and their regulation may be a key factor in determining neuronal firing frequency. The inactivation rate of Shal channels is increased by a presently unidentified class of proteins in both Drosophila and mammals. We have cloned a novel Shal channel subunit (jShalgamma1) from the jellyfish Polyorchis penicillatus that alters Shal currents from both invertebrates and vertebrates. When co-expressed with the conserved jellyfish Shal homolog jShal1, jShalgamma1 dramatically changes both the rate of inactivation and voltage range of activation and steady-state inactivation. jShalgamma1 provides fast inactivation by a classic N-type mechanism, which is independent of its effects on voltage dependence. jShalgamma1 forms functional channels only as a heteromultimer, and jShalgamma1 + jShal1 heteromultimers are functional only in a 2:2 subunit stoichiometry.
Jegla
T
T
Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Salkoff
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L
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004594:Electrophysiology; D008433:Mathematics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000502:physiology*; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D037401:Scyphozoa / Q000235:genetics*
D010446:Peptide Fragments; D015221:Potassium Channels