All Wired Up: An Exploration of the Electrical Properties of Microtubules and Tubulin

Abstract

Microtubules are hollow, cylindrical polymers of the protein α, β tubulin, that interact mechanochemically with a variety of macromolecules. Due to their mechanically robust nature, microtubules have gained attention as tracks for precisely directed transport of nanomaterials within lab-on-a-chip devices. Primarily due to the unusually negative tail-like C-termini of tubulin, recent work demonstrates that these biopolymers are also involved in a broad spectrum of intracellular electrical signaling. Microtubules and their electrostatic properties are discussed in this Review, followed by an evaluation of how these biopolymers respond mechanically to electrical stimuli, through microtubule migration, electrorotation and C-termini conformation changes. Literature focusing on how microtubules act as nanowires capable of intracellular ionic transport, charge storage, and ionic signal amplification is reviewed, illustrating how these biopolymers attenuate ionic movement in response to electrical stimuli. The Review ends with a discussion on the important questions, challenges, and future opportunities for intracellular microtubule-based electrical signaling.

Modeling Microtubule Counterion Distributions and Conductivity Using the Poisson-Boltzmann Equation

“…MTs have been shown to demonstrate a number of interesting electrical properties, including long-distance propagation of ionic signals, signal amplification, electrical oscillations, and memristive responses (Priel et al, 2006;Priel and Tuszyński, 2008;Satarić et al, 2009;Sekulić et al, 2011;Sekulić and Satarić, 2012;Cantero et al, 2018Cantero et al, , 2019Tuszynski et al, 2020). These properties have been theorized to play an important role in biological processes, and may be leveraged for the fabrication of MT nanodevices in the near future (Van den Heuvel et al, 2006;Isozaki et al, 2015;Kalra et al, 2020aKalra et al, , 2021. Of these electrical properties, ionic signal propagation is the most wellstudied, and the propagation of coherent ionic signals along MTs is a necessary component for memristive behavior and ionic signal amplification (Freedman et al, 2010;Tuszynski et al, Abbreviations: CT, C-termini; MT, microtubule; SMT, subtilisin-cleaved microtubule; PB, Poisson-Boltzmann; NLPB, non-linear Poisson-Boltzmann; LPB, linear Poisson-Boltzmann; MD, molecular dynamics.…”

Biomolecular Basis of Cellular Consciousness via Subcellular Nanobrains

“…This may allow the merging of their fields to generate the new stronger and senomic field of an emergent eukaryotic cell. In addition to the excitable plasma membrane and membranes of recycling vesicles, other cellular structures that are capable of contributing to the cellular fields are the large, bundled, vibrating elements of the cytoskeleton ( Box 2 ), such as F-actin [ 40 , 41 , 42 , 43 ] and microtubules [ 44 , 45 , 46 , 47 ]. Both excitable plasma membrane and cytoskeletal elements have been proposed to generate proto-consciousness of individual eukaryotic cells [ 22 , 48 ].…”

Low-energy amplitude-modulated radiofrequency electromagnetic fields as a systemic treatment for cancer: Review and proposed mechanisms of action

“…These potential differences provide the ion-motive forces that underlie nearly all physiological processes in cells ( 12 , 13 ). Cells also contain highly charged macromolecular structures, including microtubules, which are involved in cellular electrical signal propagation in addition to their well-known role in cell division ( 14 , 15 ). We discuss potential mechanisms of action of LEAM RF EMF exposure in patients with cancer, at cellular and subcellular levels.…”