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Reaction rate of small diffusing molecules on a cylindrical membrane

Item Type:Article
Title:Reaction rate of small diffusing molecules on a cylindrical membrane
Creators Name:Straube, R., Ward, M.J. and Falcke, M.
Abstract:Biomembranes consist of a lipid bi-layer into which proteins are embedded to fulfill numerous tasks in localized regions of the membrane. Often, the proteins have to reach these regions by simple diffusion. Motivated by the observation that IP3 receptor channels (IP3R) form clusters on the surface of the endoplasmic reticulum (ER) during ATP-induced calcium release, the reaction rate of small diffusing molecules on a cylindrical membrane is calculated based on the Smoluchowski approach. In this way, the cylindrical topology of the tubular ER is explicitly taken into account. The problem can be reduced to the solution of the diffusion equation on a finite cylindrical surface containing a small absorbing hole. The solution is constructed by matching appropriate 'inner' and 'outer' asymptotic expansions. The asymptotic results are compared with those from numerical simulations and excellent agreement is obtained. For realistic parameter sets, we find reaction rates in the range of experimentally measured clustering rates of IP3R. This supports the idea that clusters are formed by a purely diffusion limited process.
Keywords:Diffusion Limited Reaction, Cluster Rate, Asymptotic Matching, Singularly Perturbed Domains, Regular Part of the Green's Function
Source:Journal of Statistical Physics
Page Range:377-405
Date:October 2007
Official Publication:https://doi.org/10.1007/s10955-007-9371-4

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