Larsen2004_CalciumSpiking_EnzymeBinding

This a model from the article:

On the encoding and decoding of calcium signals in hepatocytes

Ann Zahle Larsen, Lars Folke Olsen and Ursula Kummera
Biophysical ChemistryVolume 107, Issue 1, 1 January 2004, Pages 83-99
14871603,

Abstract:

Many different agonists use calcium as a second messenger. Despite intensive research in intracellular calcium signalling it is an unsolved riddle how the different types of information represented by the different agonists, is encoded using the universal carrier calcium. It is also still not clear how the information encoded is decoded again into the intracellular specific information at the site of enzymes and genes. After the discovery of calcium oscillations, one likely mechanism is that information is encoded in the frequency, amplitude and waveform of the oscillations. This hypothesis has received some experimental support. However, the mechanism of decoding of oscillatory signals is still not known. Here, we study a mechanistic model of calcium oscillations, which is able to reproduce both spiking and bursting calcium oscillations. We use the model to study the decoding of calcium signals on the basis of co-operativity of calcium binding to various proteins. We show that this co-operativity offers a simple way to decode different calcium dynamics into different enzyme activities.

Note:

This model corresponds to the improved model eqn 1-7, as described by Larsen et al., 2004 implemented to investigate how the cell can decode different oscillations. This is done by introducing 2 more variables Enzyme and Product in addition to the 5 variables G-alpha, PLC, Ca_cyt, Ca_ER and Ca_mit receptor-operated model described in the first part of the paper. The receptor-operated model is itself a modified version of the model described in Kummer 2000 (PMID:10968983)