A model of IP3 receptor with a luminal calcium binding site: stochastic simulations and analysis.
We have constructed a stochastic model of the inositol 1,4,5-trisphosphate receptor-Ca2+ channel that is based on quantitative measurements of the channel's properties. It displays the observed dependence of the open probability of the channel with cytosolic [Ca2+] and [IP3] and gives values for the dwell times that agree with the observations. The model includes an explicit dependence of channel gating with luminal calcium. This not only explains several observations reported in the literature, but also provides a possible explanation of why the open probabilities and shapes of the bell-shaped curves reported in [Nature 351 (1991) 751] and in [Proc. Natl. Acad. Sci. U.S.A. 269 (1998) 7238] are so different.
Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón I (1428), Buenos Aires, Argentina. dfraiman@df.uba.ar
Daniel
D
Fraiman
Silvina Ponce
SP
Dawson
D001665:Binding Sites; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D015220:Calcium Channels / Q000737:chemistry* / Q000378:metabolism; D020013:Calcium Signaling; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008956:Models, Chemical; D011485:Protein Binding; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000378:metabolism
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D002118:Calcium