Sneyd, Dufour, 2002

Model Status

This CellML model runs in OpenCell and COR. The units have been checked and they are consistent. In the absence of published values for the initial probabilities of each channel state we have used 0.16 for A, I1, I2, and R and 0.01 for O.

Model Structure

ABSTRACT: The dynamic properties of the inositol (1,4,5)-trisphosphate (IP(3)) receptor are crucial for the control of intracellular Ca(2+), including the generation of Ca(2+) oscillations and waves. However, many models of this receptor do not agree with recent experimental data on the dynamic responses of the receptor. We construct a model of the IP(3) receptor and fit the model to dynamic and steady-state experimental data from type-2 IP(3) receptors. Our results indicate that, (i) Ca(2+) binds to the receptor using saturating, not mass-action, kinetics; (ii) Ca(2+) decreases the rate of IP(3) binding while simultaneously increasing the steady-state sensitivity of the receptor to IP(3); (iii) the rate of Ca(2+)-induced receptor activation increases with Ca(2+) and is faster than Ca(2+)-induced receptor inactivation; and (iv) IP(3) receptors are sequentially activated and inactivated by Ca(2+) even when IP(3) is bound. Our results emphasize that measurement of steady-state properties alone is insufficient to characterize the functional properties of the receptor.

The original paper reference is cited below:

A dynamic model of the type-2 inositol triphosphate receptor, James Sneyd and Jean-Francois Dufour, 2002, Proceedings of the National Academy of Sciences , 99, 2398-2403. PubMed ID: 11842185

A simplified diagram of the IPR model, where R represents the free receptor, O is the open state of the channel, A is the activated state of the channel and I1, I2, and S are three inactive states.
Derived from workspace Sneyd, Dufour, 2002 at changeset 7eeb9824c6ae.
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