Some kind of standardization has already started to occur in this direction , at least for enzyme kinetics. 3.4. Modeling Gene Expression and http://www.selleckchem.com/products/Tubacin.html protein Production We demonstrate the generic modeling approach by beginning at the gene
expression level. Of particular importance for heat stress responses are MSN2/4, as discussed before. For simplicity, Inhibitors,research,lifescience,medical it is useful to model these two transcription regulators as just one MSN gene or protein. This simplification seems to be supported by their structural and functional similarity. Associated with this transcription factor are a basal level of expression and the provision that heat might slightly increase this expression. As discussed previously, the activity of MSN also depends on protein kinase A (PKA), which itself is affected by cAMP and stress. A recent model  integrates these phenomena. It describes the PKA system in great detail and Inhibitors,research,lifescience,medical leads to the conclusion that cAMP-PKA and stress may cause an oscillatory shuttling of Msn2p between nucleus and cytoplasm. However, the model does not describe mechanistically or operationally how heat stress changes the localization of the MSN protein. Inhibitors,research,lifescience,medical Thus, by adjusting the main concepts of this model to our purposes, one might propose to model the change in localization according to the scheme in Figure 2, where heat stress promotes nuclear localization, whereas activation
of PKA favors cytosolic localization. In this approach, PKA is modeled in one of two states, namely, activated (PKAC) or
inactivated (PKARC). The conversion to the activated state depends on glucose, whereas heat stress inactivates PKA. Once in the nucleus, the Inhibitors,research,lifescience,medical Msn protein activates the expression of genes coding for some of the enzymes associated with heat stress (TPS1,2; HXT5; ZWF1; HXK1; GLK1; PGM2; GPM2; GSY2; GLG1; NTH1) and with generic chaperonins that possess refolding functionality (see later and Figure 3). In a canonical model, Inhibitors,research,lifescience,medical the qualitative description of the various table 5 influences is straightforwardly translated into power-law terms that contain each contributing factor as a variable with an exponent [21,25]. Figure 3 Scheme of the competing forces affecting protein folding AV-951 and unfolding. Heat stress (HS) causes the unfolding of proteins, while chaperonins promote their refolding. Trehalose functions as a protein stabilizer preventing denaturation and aggregation; … The expression of HSF1 does not seem to change much with heat stress , and it is therefore not necessary to model its gene expression. Instead, one considers the total amount of protein as constant and partitions this amount into different activity states. Specifically, HSF1p can exist in three states: free, bound to HSE, or bound to repressor proteins (Figure 1). Hsf1p is kept inactivated by binding to a number of proteins with similar function.