FIGURE 13.

Signal integration and multiple protein-protein interactions. The ability of single ligand (α) stimulation (left panel) to exert its full effects on cellular physiology is dependent on the ability of its signal proteins to interact with the receptor in a concerted and controlled manner. Signal transduction accessory proteins are initially created in the endoplasmic reticulum (A), before export and loose assembly in Golgi/vesicles (B), and before eventual stable interaction with a cell surface receptor (C). Single ligand stimulation (α) results in the differential association of stable and de novo signaling factors with the receptor at the membrane (D). Eventually, the complex of signaling proteins (encrypton) may dissociate from the receptor (E) and further change certain factors (F) before affecting genetic transcription. With multiple ligand stimulation (α, β), however, the relative apportioning of the stable signaling encryptons (1) with the active receptors (2) may be qualitatively/quantitatively different. Therefore, the nature of the disengaged signaling encrypton may be distinct (3). Because of the differences in encrypton complementation, alterations in transcriptional regulation may occur effecting distinct metabolic cellular outputs (4).