Role of the terminal domains in sodium channel localization.
Voltage-gated sodium channels are membrane proteins that initiate action potentials in neurons following membrane depolarization. Members of this family show differential distribution at the subcellular level. The mechanisms underlying the targeting of these isoforms are not understood. However, their specificity is important because the isoforms can change the excitability of the membrane due to differences in their electrophysiological properties. In this study, chimeras generated between Na(V)1.2 and Na(V)1.6 were used to test channel domains for sequence that would allow Na(V)1.2 to localize to unmyelinated axons when Na(V)1.6 could not. We show that the N-terminal 202 amino acids of the Na(V)1.2 channel can mediate membrane domain-specific sorting in polarized epithelial cells and are necessary but not sufficient for localizing the isoform to the axons of cultured neurons. The domain-sorting signal is in the region between amino acids 110-202 of the Na(V)1.2 channel. The C-terminal 451 amino acids of Na(V)1.2 likely contain determinants that interact with neuron-specific factors to direct Na(V)1.2 to the axon.
Lee
Annie
A
Department of Microbiology & Molecular Genetics and Anatomy & Neurobiology, University of California at Irvine, Irvine, CA 92697-4025, USA.
Goldin
Alan L
AL
D000818:Animals; D001369:Axons / Q000378:metabolism*; D002460:Cell Line; D004285:Dogs; D062557:NAV1.6 Voltage-Gated Sodium Channel; D009928:Organ Specificity / Q000502:physiology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D021382:Protein Sorting Signals / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus
D062557:NAV1.6 Voltage-Gated Sodium Channel; D020033:Protein Isoforms; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; C507811:Scn8a protein, rat; D015222:Sodium Channels