Effects on adenylyl cyclase

Clark MJ, Harrison C, Zhong H, et al Endogenous RGS protein action modulates mu-opioid signaling through Galphao effects on adenylyl cyclase, extracellular signal-regulated kinases, and intracellular calcium pathways. J Biol Chem 278 9418-9425, 2003... 

The first members of the Gi subfamily to be discovered displayed an inhibitory effect on adenylyl cyclase, thus the name Gi, for inhibitory G-proteins. Further members of the Gi subfamily have phospholipase C as the corresponding effector molecule. Signal transmission via phospholipase C flows into the inositol triphosphate and diacylglyce-rol pathways (see Chapter 6). 

The cooperation of the different regulatory signals that may have an effect on adenylyl cyclase is not yet imderstood. Due to the existence of different subtypes of adenylyl cyclase and their various regulation patterns, it is assumed that the individual subtypes have specific roles in different cell compartments, cells and tissues, and are each subject to defined regulatory processes. 

Palmer TM, Harris CA, Coote J, Stiles GL (1997) Induction of multiple effects on adenylyl cyclase regulation by chronic activation of the human A3 adenosine receptor. Mol Pharmacol 52(4) 632-640... 

The a subunits and the Py complex have actions independent of those on adenylyl cyclase (see Figure 43-4 and Table 43-3). Some forms of tt stimulate channels and inhibit Ca channels, and some ttj molecules have the opposite effects. Members of the G, family activate the phospholipase C group of enzymes. The py complexes have been associated with channel stimulation and phospholipase C activation. G proteins are involved in many important biologic processes in addition to hormone action. Notable examples include olfaction (oColf) <1 vision (aj. Some examples are listed in Table 43-3. GPCRs are implicated in a number of diseases and are major targets for pharmaceutical agents. 

Effect of Cholera Toxin on Adenylyl Cyclase The gram-negative bacterium Vibrio cholerae... 

It was later found that some effects of dopamine did not involve stimulation of adenylyl cyclase. Particularly, in the pituitary gland, dopamine was found to inhibit prolactin release without stimulating adenylyl cyclase activity and even by inhibiting it (Spano et al., 1978 De Camilli et al., 1979). Moreover, the antipsychotic drug sulpiride blocked the dopamine-induced release of prolactin in the pituitary gland but was unable to antagonize the dopamine response on adenylyl cyclase activity in the striatum (Trabucchi et al., 1975). These observations led to the hypothesis that the dopamine receptors exist as two... 

Fan F, Tao Q, Abood M, Martin BR (1996) Cannabinoid receptor down-regulation without alteration of the inhibitory effect of CP 55,940 on adenylyl cyclase in the cerebellum of CP 55,940-tolerant mice. Brain Res 706 13-20... 

Toward the goal of understanding potential transduction mechanisms associated with adenosine receptor activation in porcine atria, the effect of the Aj-selective agonist cyclopentyl adenosine (CPA) on adenylyl cyclase activity was evaluated. CPA (1 fM) inhibited basal adenylyl cyclase activity in a GTP-dependent manner with maximal inhibition by CPA occurring at a GTP concentration of 100 /iM (Figure 3). The inhibition of... 

The cAMP formed by adenylyl cyclase (Figure 15.20) does not persist because 5 -phosphodiesterase activity prevalent in cells hydrolyzes cAMP to give 5 -AMP. Caffeine inhibits 5 -phosphodi-esterase activity. Describe the effects on glycogen phosphorylase activity that arise as a consequence of drinking lots of caffeinated coffee. 

FIGURE 9.14 Effects of adenosine receptor agonist 2-chloro-adenosine on vascular perfusion pressure of isolated perfused rat kidneys. Minor effects seen in untreated kidneys (filled circles) and pronounced vasoconstriction while vasodilatation in kidneys coperfused with subthreshold concentrations of a-adrenoceptor vasoconstrictor methoxamine and vasodilatatory activation of adenylyl cyclase with forskolin (open circles). Redrawn from [49]. 

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