# BG_PLC

### About this model

This is a bond-graph model of the metabolism of the phospholipase-C beta variant (PLC) and the associated Gq protein in the mammalian cell.

INPUTS:

- Gq protein (Gq)
OUTPUTS:

- Change in molar amount of diacylglycerol (DAG), inositol trisphosphate (IP3), calcium (Ca)
REACTIONS:

- R0: Conversion of DAG into phosphatidylcholine (PC)
- R1: Conversion of IP3 into inositol (Ino)
- R2: PLC complex CaPLC catalysing the splitting of phosphatidylinositol biphosphate (PIP2) into DAG and IP3
- R3: Similar to R2, but with enzyme complex CaGqPLC
- R4: Binding of Ca and PLC
- R5: Binding of Gq and PLC
- R6: Binding of Ca and GqPLC
- R7: Unbinding of Gq from CaGqPLC
- R8: Unbinding of Gq (in G*GDP form) from CaGqPLC

### Model status

The current CellML implementation runs in OpenCOR.

### Model overview

This model is based on existing kinetic model, where the mathematics are translated into the bond-graph formalism. This describes the model in energetic terms and forces adherence to the laws of thermodynamics.

For the above bond-graphs, a '0' node refers to a junction where all chemical potentials are the same. A '1' node refers to all fluxes being the same going in and out of the junction.

Abbreviation | Name |
---|---|

PLC | Phospholipase-C (beta variant) |

Ca | Calcium ion |

Gq | Gq protein |

DAG | Diacylglycerol |

IP3 | Inositol trisphosphate |

Ino | Inositol |

PIP2 | Phosphatidylinositol biphosphate |

PC | Phosphatidylcholine |

#### Parameter finding

A description of the process to find bond-graph parameters is shown in the folder parameter_finder, which relies on the:

- stoichiometry of system
- kinetic constants for forward/reverse reactions

- If not already, all reactions are made reversible by assigning a small value to the reverse direction.

Here, this solve process is performed in Python.

### Original kinetic model

Bhalla and Iyengar: Emergent properties of networks of biological signaling pathways.