Abstract
Intracellular Ca signaling is governed by diffusion and buffering
of Ca ions. Mobile endogenous buffers increase the redistribution
of Ca ions and tend to restrict the regions of elevated Ca concentrations
to the close vicinity of the channel. These Ca microdomains dominate
fast Ca signaling, as observed, e.g., in synaptic transmission. The
steady-state solution of the linearized differential equations of
buffered Ca diffusion, as developed by Neher and Naraghi and Neher,
will be reviewed and generalized to the case of more than two buffers.
Immobile buffers do not enter the steady-state equations, but instead
slow down Ca diffusion and prolong the time to reach the steady state.
Based on this phenomenon, a quite different putative mechanism to
localize Ca will be suggested that is likely to be realized in photoreceptors
where Ca source, Ca sink, and Ca sensor form a complex, as was recently
reported.
- 11898855
- binding,
- calcium
- calcium,
- channels,
- diffusion,
- gov't,
- kinetics,
- models,
- non-u.s.
- protein
- research
- signal
- statistical,
- structure,
- support,
- tertiary,
- transduction,
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