GATING OF THE Ca2+ CHANNEL AND THE KINETICS OF ELEMENTARY CALCIUM RELEASE EVENTS

IRINA BARAN

Biophysics Department, “Carol Davila” University of Medicine and Pharmaceutics, 8, Eroilor Sanitari Blvd, 050474 Bucharest, Romania

Abstract. By using a three-module decomposition of the inositol 1,4,5-trisphosphate receptor we describe both steady-state and dynamic features of the channel activity. Good agreement with published experimental data is obtained by estimating the errors introduced by missed events during single channel recordings. Inactivation as well as incremental detection at the receptor level can be well reproduced by the model in both deterministic and stochastic approaches. By simulating calcium release at individual sub cellular sites we find that the kinetics of elementary calcium events can be consistently explained by assuming that receptors are disposed as clusters with outputs located on the membrane of thin tubules of the endoplasmic reticulum, rather than assuming a spherical or hemispherical symmetry around a point source as generally accepted.

Author’s e-mail: virbaran@yahoo.com

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