Gene regulatory networks expression

Gene regulatory network Spatial and temporal expression patterns of Drosophila segment polarity genes (Albert and Othmer, 2003)... 

Fig. 1. The generalized protein-protein interaction network that includes (A) direct protein-protein interactions such as in the signal transduction pathway, (B) enzyme-enzyme relations in the metabolic pathway, and (C) transcription factor-expressed gene product relations in the gene regulatory pathway. The interactions in (B) and (C) are termed indirect protein-protein interactions.

Activator proteins themselves can be boimd in regulatory networks, as shown in the example of the cyclins (chapter 14). The function of an activator protein can be regulated at the level of gene expression, degradation, or post-translational modification (e.g. protein phosphorylation). 

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