Structural Requirements for Interaction of Sodium Channel β1 Subunits with Ankyrin*

By J. Malhotra, M. Koopmann, K. Kazen-Gillespie, Nicholas Fettman, M. Hortsch, L. Isom. Journal of Biological Chemistry, 2002

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Sodium channel β subunits modulate channel kinetic properties and cell surface expression levels and function as cell adhesion molecules. β1 and β2 participate in homophilic cell adhesion resulting in ankyrin recruitment to cell contact sites. We hypothesized that a tyrosine residue in the cytoplasmic domain of β1 may be important for ankyrin recruitment and tested our hypothesis using β1 mutants replacing Tyr181 with alanine (β1Y181A), phenylalanine (β1Y181F), or glutamate (β1Y181E), or a truncated construct deleting all residues beyond Tyr181(β1L182STOP). Ankyrin recruitment was observed in β1L182STOP, showing that residues Ile166-Tyr181 contain the major ankyrin recruiting activity of β1. Ankyrin recruitment was abolished in β1Y181E, suggesting that tyrosine phosphorylation of β1 may inhibit β1-ankyrin interactions. AnkyrinG and β1 associate in rat brain membranes and in transfected cells expressing β1 and ankyrinG in the absence of sodium channel α subunits. β1 subunits are recognized by anti-phosphotyrosine antibodies following treatment of these cell lines with fibroblast growth factor. β1 and ankryinG association is not detectable in cells following treatment with fibroblast growth factor. AnkyrinG and β1Y181E do not associate even in the absence of fibroblast growth factor treatment. β1 subunit-mediated cell adhesion and ankyrin recruitment may contribute to sodium channel placement at nodes of Ranvier. The phosphorylation state of β1Y181 may be a critical regulatory step in these developmental processes.

Subfields: Cellular and Molecular Neuroscience, Molecular Biology, Physiology

View Paper: https://www.semanticscholar.org/paper/f031b414b40fc35d1c145984559e6e9fdd847287

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Citations in the corpus

The local differentiation of myelinated axons at nodes of Ranvier (2003, background): “and this interaction is regulated by tyrosine phosphorylatio”
Sodium Channel β4, a New Disulfide-Linked Auxiliary Subunit with Similarity to β2 (2003, background): “…et al., 2001), neurofascin (Ratcliffe et al., 2001), and tenascin (Srinivasan et al., 1998; Xiao et al., 1999). subunits also participate in homophilic cell interactions and interact with ankyrin, thus localizing channels to sites of cell– cell interaction (Malhotra et al., 2000, 2002).”
Molecular physiology of cardiac repolarization. (2005, background): “6) and/or interactions with other components of the actin cytoskeleton (135).”
Voltage-gated ion channels and gating modifier toxins. (2007, background): “The Na subunits are a recent evolutionary addition to the family of ion channel associated proteins, as2001 Malhotra et al., 2002 V β they have only been identified in vertebrates.”