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Fig. 2 | Biology Direct

Fig. 2

From: Models of buffering of dosage imbalances in protein complexes

Fig. 2

Buffer effects in the assembly of a heterodimer. a The monomers A and B are involved in competing reactions: their degradation or their dimerization. b Alternative scenario in which both A and B have a preferential conformation to interact with each other (i.e. AI and BI). Conformations AII and BII do not lead to dimers. Note that the parameters of synthesis and degradation encapsulate information on both mRNA and protein in this simplified model, but we assume that no buffering occurs at the transcriptional level. c Buffering response of heterodimer AB formation to changing the input concentration of one monomer. As mentioned in the text, here we consider for simplicity that A and B are synthesized in a very short time scale compared to the rest of the reactions. So we deal with input concentrations and not with parameters of synthesis (as will be the case in Fig. 3). The ordinates represent the % of AB when either A0 or B0 are changed (0.5X or 1.5X, "mutated" condition) with respect to A0 = B0 ("wild-type", wt). The results were obtained with the biochemical simulator GEPASI, which solves numerically the chemical and the underlying differential equations [40]. If normally A0 = B0 = 1nM, DA = DB (here called D) and kAB > > D, at a specific D/kAB value, halving the input amount of either monomer (upper panel) leads to >57 % of dimer in such (rather artificial) conditions of irreversibility. Operating at the same D/kAB value leads to 123 % of AB output when A0 or B0 are increased by 150 %. d Response of heterodimer AB formation to changing the input concentration of one monomer (when one of them can be degraded and the other not). In this case A0 = B0 = 1nM, DA = 0.01 min−1 and DB = 0 min−1

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