Model of ionic currents through microtubule nanopores and the lumen

Abstract

It has been suggested that microtubules and other cytoskeletal filaments may act as electrical transmission lines. An electrical circuit model of the microtubule is constructed incorporating features of its cylindrical structure with nanopores in its walls. This model is used to study how ionic conductance along the lumen is affected by flux through the nanopores when an external potential is applied across its two ends. Based on the results of Brownian dynamics simulations, the nanopores were found to have asymmetric inner and outer conductances, manifested as nonlinear IV curves. Our simulations indicate that a combination of this asymmetry and an internal voltage source arising from the motion of the C-terminal tails causes a net current to be pumped across the microtubule wall and propagate down the microtubule through the lumen. This effect is demonstrated to enhance and add directly to the longitudinal current through the lumen resulting from an external voltage source, and could be significant in amplifying low-intensity endogenous currents within the cellular environment or as a nano-bioelectronic device.

Role of nonlinear localized Ca2+ pulses along microtubules in tuning the mechano–sensitivity of hair cells

“…This stream is charging elementary unit capacitors and partly leaking through nano-pores into MT lumen. In that respect, in silico estimations of respective resistivity published by Freedman (Freedman et al, 2010) is adopted as follows:…”

“…In the order hand, the conductance of both nano-pores is given as a sum of pretty different components reflecting difference in two types of nano-pores (Freedman et al, 2010) S, 10 7 . Instead of two unknown functions (i n , v n ), it is convenient to introduce just one auxiliary function u n (x, t),…”

“…A is the cross section area of a CIC around tubulin dimer. , between neighbouring tubulin dimers within a MT there are two kinds of nano-pores, which can permit the ions from pertaining condensed ionic cloud to leak into the MT lumen(Freedman et al, 2010), seeFig. 7.…”

Ionic Pulses along Cytoskeletal Protophilaments

“…Recently the more advanced version of the same concept was presented [14] in which the N P s are treated according to within the numerical simulations performed the group led by Tuszynski [17].…”

Microtubule Ionic Conduction and Its Implications for Higher Cognitive Functions

“…The latest research in this area generated an electric circuit model of the MT which incorporates not only the C-terminal tails, but also the nanopores within the MT wall, thus including not only ionic conductance along the outer surface of the MT, but conductance through the MT wall, and in the lumen as well [73]. This latest model effectively includes a 3D representation of the MT with ions flowing both along its surface and across it, in and out of the luminal space.…”