Cloning of ShIII (Shaw-Like) cDNAs Encoding a Novel High-Voltage-Activating, TEA-Sensitive, Type-A K$^{+}$ Channel

• Published in: Proceedings of the Royal Society. B, Biological sciences Biological sciences, 1992-04, Vol.248 (1321), p.9-18
• Main Authors: De Miera, Eleazar Vega-saenz, Moreno, Herman, Fruhling, David, Kentros, Clifford, Rudy, Bernardo
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acids; Animals; Base Sequence; Blotting, Northern; Brain - physiology; Cloning, Molecular - methods; Complementary DNA; DNA - genetics; DNA - isolation & purification; Electric current; Electric potential; Female; Gene Library; Genes; Mammals; Membrane Potentials - drug effects; Molecular Sequence Data; Multigene Family; Neurons; Oocytes; Oocytes - physiology; Polymerase Chain Reaction - methods; Potassium channels; Potassium Channels - drug effects; Potassium Channels - genetics; Potassium Channels - physiology; Proteins; Rats; Rats, Inbred Strains; RNA - genetics; RNA - isolation & purification; Sequence Homology, Nucleic Acid; Steady state current; Tetraethylammonium; Tetraethylammonium Compounds - pharmacology; Transcription, Genetic; Xenopus laevis
• ISSN: 0962-8452; 1471-2954
• DOI: 10.1098/rspb.1992.0036

Transient voltage-dependent potassium (K+) currents, also known as A currents, have been of great interest to neurophysiologists due to their special roles in neuronal excitability. Several cDNAs encoding transcripts expressing A currents have been characterized. Recently, a cDNA (K ShIIIC or Raw3) was isolated which expresses an unusual A current that is highly sensitive to TEA, and activates at potentials more positive than —20 mV. Channels containing this protein may have specialized roles in modulating the electrical behaviour of neurons. Here we report the isolation and characterization of two rat cDNAs corresponding to two alternatively spliced transcripts (KShlllD . 1 and KShIIID .2 ) from another gene (KShlllD ) of the same subfamily as KShlllC , the ShIll or Shaw-related gene subfamily. KShIIID .1 also expresses an unusual high-voltage-activating, TEA-sensitive A-type channel. There are, however, significant differences between KShlllC and KShlllD channels which may have interesting functional consequences. The two most im portant differences are: (i) KShlllD channels conduct in the steady-state over a much broader window of potentials than KShlllC ; this reflects differences between the kinetic schemes of the two channels; and (ii) KShlllD inactivates with significantly slower kinetics than KShlllC . The identification of KShlllD transcripts contributes to our knowledge of the molecular components that may determine the functional diversity of A currents and provides exciting opportunities to increase our understanding of the structure and function of K + channels.