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Ca2+ diffusion modulates the temporal characteristics of the signals upon co-localization.

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posted on 2019-08-19, 17:37 authored by Audrey Denizot, Misa Arizono, U. Valentin Nägerl, Hédi Soula, Hugues Berry

Representative simulations of the particle-based model showing both calcium trace and number of open IP3R for co-localized calcium sources (Rγ = 0) in the case of slow calcium diffusion (A) or perfect-mixing of calcium (B). The red crosses show peak locations from automatic detection. The impact of calcium diffusion coefficient DCa on peak frequency (C) and the amount of puff (D) are shown for different values of the co-localization parameter Rγ: from Rγ = 0 (IP3R are not clustered but co-localized with other calcium sources) to Rγ = 100 (IP3R are neither clustered nor co-localized). The puff ratio quantifies the fraction of peaks that are puffs. (E) and (F) respectively present the probabilities that IP3R closure results from binding of a Ca2+ to the inactivating site (probability to switch to state {111}, P110−>111) or unbinding of an IP3 (probability to switch to state {100}, P110−>100) depending on DCa and on Rγ. Probability of closure due to Ca2+ unbinding from activating site, P110−>010 can be deduced from 1 = P110−>010 + P110−>100+P110−>111. Data are presented as mean ± standard deviation over 20 simulations. Lines are guide for the eyes. Note that the x-axis scale in (C), (D), (E) and (F) is not regularly spaced. Other parameters: η = 1 (no clustering), a1 = 1 a.u, μ = 50 a.u.

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