Voltage-gated K+ channels contain multiple intersubunit association sites

Li Wei Tu, Vincent Santarelli, Zu Fang Sheng, William Skach, Debkumar Pain, Carol Deutsch

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    79 Scopus citations

    Abstract

    A domain in the cytoplasmic NH2 terminus of voltage-gated K+ channels supervises the proper assembly of specific tetrameric channels (Li, M., Jan, J. M., and Jan, L. Y. (1992) Science 257, 1225-1230; Shen, N. V., Chen X., Boyer, M. M., and Pfaffinger, P. (1993) Neuron 11, 67-76). It is referred to as a first tetramerization domain, or T1 (Shen, N. V., Chen X., Boyer, M. M., and Pfaffinger, P. (1993) Neuron 11, 67-76). However, a deletion mutant of Kv1.3 that lacks the first 141 amino acids, Kv1.3 (T1-) forms functional channels, suggesting that additional association sites in the central core of Kv1.3 mediate oligomerization. To characterize these sites, we have tested the abilities of cRNA Kv1.3 (T1-) fragments coinjected with Kv1.3 (T1-) to suppress current in Xenopus oocytes. The fragments include portions of the six putative transmembrane segments, S1 through S6, specifically: S1, S1-S2, S1-S2-S3, S2-S3, S2-S3-S4, S3-S4, S3-S4-S5, S2 through COOH, S3 through COOH, S4 through COOH, and S5-S6-COOH. Electrophysiologic experiments show that the fragments S1-S2-S3, S3-S4-S5, S2 through COOH, and S3 through COOH strongly suppress Kv1.3 (T1-) current, while others do not. Suppression of expressed current is due to specific effects of the translated peptide Kv1.3 fragments, as validated by in vivo immunoprecipitation studies of a strong suppressor and a nonsuppressor. Pulse-chase experiments indicate that translation of truncated peptide fragments neither prevents translation of Kv1.3 (T1-) nor increases its rate of degradation. Co-immunoprecipitation experiments suggest that suppression involves direct association of a peptide fragment with Kv1.3 (T1-). Fragments that strongly suppress Kv1.3 (T1-) also suppress an analogous NH2-terminal deletion mutant of Kv2.1 (Kv2.1 (ΔN139)), an isoform belonging to a different subfamily. Our results indicate that sites in the central core of Kv1.3 facilitate intersubunit association and that there are suppression sites in the central core, which are promiscuous across voltage- gated K+ channel subfamilies.

    Original languageEnglish (US)
    Pages (from-to)18904-18911
    Number of pages8
    JournalJournal of Biological Chemistry
    Volume271
    Issue number31
    DOIs
    StatePublished - 1996

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Biology
    • Cell Biology

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