Towards a mathematical model of the cAMP pathway in S. cerevisiae
© Williamson et al; licensee BioMed Central Ltd. 2007
Published: 8 May 2007
The small, diffusible molecule cAMP plays a key signalling role in almost all organisms. In S. cerevisiae, cAMP is synthesized by adenylate cyclase , and hydrolyzed by the phosphodiesterases Pde1p and Pde2p [2, 3]. The only function of cAMP in yeast is to activate PKA (Protein Kinase A). A molecule of PKA is a tetramer consisting of two catalytic (C) and two regulatory (R) subunits. Cyclic AMP binds to the R subunit, allowing its dissociation from C, allowing C to become catalytically active. PKA is believed to activate Pde1p , as well as indirectly inhibit the activity of adenylate cyclase . We have created two mathematical models (one simplified and one detailed) in order to better understand the mechanisms of PKA activation. We have also created a model to investigate the complete cAMP pathway.
The models of PKA activation can reproduce events seen in vivo, but the detailed model also allows for concentrations of intermediates to be predicted. This could give insights into the mechanism by which PKA activation is regulated. The complete pathway model can reproduce phosphodiesterase knockout mutant phenotypes seen in vivo, as well as predicting that the cAMP level oscillates before reaching a steady-state. Further analysis and development of these models should give further insights into the cAMP pathway in yeast.
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