Palmitoylation of the S0-S1 Linker Regulates Cell Surface Expression of Voltage- and Calcium-activated Potassium (BK) Channels

O. Jeffries, N. Geiger, I. C. M. Rowe, L. J. Tian, H. McClafferty, L. Chen, D. L. Bi, H. G. Knaus, P. Ruth, M. J. Shipston

Research output: Contribution to journalArticlepeer-review

Abstract

S-Palmitoylation is rapidly emerging as an important post-translational mechanism to regulate ion channels. We have previously demonstrated that large conductance calcium-and voltage-activated potassium (BK) channels are palmitoylated within an alternatively spliced (STREX) insert. However, these studies also revealed that additional site(s) for palmitoylation must exist outside of the STREX insert, although the identity or the functional significance of these palmitoylated cysteine residues are unknown. Here, we demonstrate that BK channels are palmitoylated at a cluster of evolutionary conserved cysteine residues (Cys-53, Cys-54, and Cys-56) within the intracellular linker between the S0 and S1 transmembrane domains. Mutation of Cys-53, Cys-54, and Cys-56 completely abolished palmitoylation of BK channels lacking the STREX insert (ZERO variant). Palmitoylation allows the S0-S1 linker to associate with the plasma membrane but has no effect on single channel conductance or the calcium/voltage sensitivity. Rather, S0-S1 linker palmitoylation is a critical determinant of cell surface expression of BK channels, as steady state surface expression levels are reduced by similar to 55% in the C53:54:56 A mutant. STREX variant channels that could not be palmitoylated in the S0-S1 linker also displayed significantly reduced cell surface expression even though STREX insert palmitoylation was unaffected. Thus our work reveals the functional independence of two distinct palmitoylation-dependent membrane interaction domains within the same channel protein and demonstrates the critical role of S0-S1 linker palmitoylation in the control of BK channel cell surface expression.
Original languageEnglish
Pages (from-to)33307-33314
Number of pages8
JournalJournal of Biological Chemistry
Volume285
Issue number43
DOIs
Publication statusPublished - Oct 2010

Keywords

  • Ion channels
  • Membrane proteins
  • Membrane trafficking
  • Potassium channels
  • Protein palmitoylation

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