Activator protein inhibition

Bacteria Escherichia coli Release of glucose inhibition of enzyme induction (see Catabolite repression). Initiation of mRNA synthesis mediated by a specific cAMP receptor protein (catabolite gene activator protein). Inhibition of the degradation of mRNA bound to ribosomes. Stimulation of the synthesis of many enzymes... 

Bouaboula, M., Perrachon, S., Milligan, L., Canatt, X., Rinaldi-Carmona, M., Portier, M., Barth, F., Calandra, B., Pecceu, F., Lupker, J., Maffrand, J.-P., Le Fur, G., and Casellas, P. (1997). A selective inverse agonist for central cannabinoid receptor inhibits mitogen-activated protein kinase activation stimulated by insulin or insulin-like growth factor. J. Biol. Ckem. 272 22330-22339. 

Tetracycline and its derivative doxycycline are antibiotics widely used in the treatment of bacterial infections. They also exert an antimalarial activity. Tetracyclines inhibit the binding of aminoacyl-tRNA to the ribosome during protein synthesis. 

Functionally, the Dl-like receptors (Dl, D5) are coupled to the G protein Gas and thus can stimulate adenylyl cyclase. The D2-like receptors (D2, D3, and D4) couple to pertussis toxin sensitive G proteins (Gai/0), and consequently inhibit adenylyl cyclase activity. While the Dl-like receptors almost exclusively signal through Gas-mediated activation of adenylyl cyclase, the D2-like receptors have been reported to modulate the activity of a plethora of signaling molecules and pathways. Many of these actions are mediated through the G(3y subunit. Some of these molecules and pathways include the calcium channels, potassium channels, sodium-hydrogen exchanger, arachidonic acid release, and mitogen-activated protein kinase pathways. 

STAT signaling occurs within minutes following activation but also underlies rapid deactivation by cytoplasmic phosphatases or antagonistic factors such as members of the SOCS-proteins themselves induced by activated STATs. Another group of proteins called PIAS (proteins that inhibit active STATs) inhibit binding of activated STATs to their target DNA sequences... 

Muscarinic acetylcholine receptors (mAChRs) form a class of cell surface receptors that are activated upon binding of the neurotransmitter, acetylcholine. Structurally and functionally, mAChRs are prototypical members of the superfamily of G protein-coupled receptors. Following acetylcholine binding, the activated mAChRs interact with distinct classes of heterotrimeric G proteins resulting in the activation or inhibition of distinct downstream signaling cascades. 

Activation of Mi, M3, and M5 mAChRs does not only lead to the generation of IP3 followed by the mobilization of intracellular Ca2+, but also results in the stimulation of phospholipase A2, phospholipase D, and various tyrosine kinases. Similarly, M2 and M4 receptor activation does not only mediate the inhibition of adenylyl cyclase, but also induces other biochemical responses including augmentation of phospholipase A2 activity. Moreover, the stimulation of different mAChR subtypes is also linked to the activation of different classes of mitogen-activated protein kinases (MAP kinases), resulting in specific effects on gene expression and cell growth or differentiation. 

The OP group of receptois share common effector mechanisms. All receptois couple via pertussis toxin-sensitive Go and Gi proteins leading to (i) inhibition of adenylate cyclase (ii) reduction of Ca2+ currents via diverse Ca2+ channels (hi) activation of inward rectifying K+ channels. In addition, the majority of these receptors cause the activation of phospholipase A2 (PLA2), phospholipase C 3 (PLC 3), phospholipase D2 and of MAP (mitogen-activated protein) kinase (Table 3). 

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