Adenylyl cyclase adenylate

Acyl-CoA Synthetase Adaptive Immunity Adaptor Proteins Addiction Addison s Disease Additive Interaction Adenosine Adenosine Receptors Adenoviruses Adenylate Cyclase Adenylyl Cyclases ADH ADHD... 

Adenylyl cyclases. See Adenylate cyclase Adenylyl groups... 

Adenoviridae Adenovirus, type 2 Adenylate cyclase Adenyl cyclase O-Adenylylation Adenylyl cyclase... 

Adenylyl cyclase (preferred) Adenylate cyclase Adenyl cyclase (original) ATP pyrophosphate lyase Cyclizing (E.C.4.6.1.1.)... 

Adenyl cyclase The enzyme (also known as adenylate, or adenylyl cyclase) that catalyses the formation of the second messenger cyclic adenosine-.l A -monophosphate (cAMP) from ATP following the activation of a Gs protein-coupled receptor. 

Adenosine binds to adenosine receptors (AD-Rs) (subtypes Ah A2A, A2b and A3). Ap and Ap R activation gives Gai-mediated inhibition of adenylyl cyclase (resulting in decreased cAMP) and Gai/Gao-mediated activation of a K+ channel (with a de-excitatory hyperpolarizing effect). A2A and A2B activation gives Gas-mediated stimulation of adenylate cyclase (resulting in elevated cAMP). Adenosine acting via particular receptors variously has cardioprotective, neuroprotective, sedative, anticonvulsant, soporific, vasodilatory and bronchoconstrictive effects. The plant-derived methylxanthines theophylline and caffeine are adenosine A1 and A2 receptor antagonists (Table 5.1). 

The cyclic nucleotides adenosine 3, 5 -cyclic monophosphate (cyclic AMP (cAMP)) and guanosine 3, 5 -cyc.lic monophosphate (cyclic GMP (c.GMP)) are second messengers generated by adenylyl (adenylate) cyclase (AC) and guanylyl (guanylate) cyclase (GC), respectively, in response to receptor occupation by particular primary messengers , that is,... 

AC, adenylyl cyclase, adenylate cyclase ACAT, acylCoA cholesterol... 

Adenyl cyclase, also referred to as adenylate cyclase or adenylyl cyclase, is a lyase enzyme (in biochemistry, a lyase is an enzyme that catalyses the breaking of various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure. Lyases differ from other enzymes in that they only require one substrate for the reaction in one direction, but two substrates for the reverse reaction). There are 10 known adenyl cyclases in mammals, ADCYl through ADCYIO. 

The ATP-regenerating system may complicate the analysis because of its possible influence on the adenylate cyclase activity. For example, 5 -adenylyl imidodiphosphate (AMP-PNP) labelled with a- P, an analogue of ATP containing Nitrogen substituted for Oxygen between the terminal phosphates, has been used to circumvent the problems encountered in maintaining the substrate concentration during kinetic studies of adenylate cyclase activity [109]. AMP-PNP is a substrate for adenylate cyclase and is only slowly hydrolysed by ATPase. Unlabelled AMP-PNP... 

Of the effector systems that have been implicated in the transduction mechanisms for opioid receptors, the best studied is opioid inhibition of adenylyl cyclase (see Refs. 69, 97-99 for reviews). Thus binding of an agonist to opioid receptors inhibits the activity of adenylyl cyclase and decreases intracellular cAMP in a number of different tissues. Pertussis toxin sensitivity of opioid inhibition of adenylyl cyclase has been demonstrated in many systems, indicating the involvement of either Gi or Go in the transduction mechanism. Agonist activation of all three types of cloned opioid receptors to inhibit adenyl cyclase has been demonstrated (see Ref 100 and references cited therein). There is also some evidence that (M and 8 opioid receptors can stimulate adenylyl cyclase in certain tissues (see Refs. 69, 97 for reviews). There are conflicting reports on whether k opioid receptors stimulate or inhibit phosphatidylinositol turnover in some tissues (see Ref 100) 8 and fx receptors, however, do not appear to be coupled to phosphatidylinositol turnover in neuroblastoma cell lines NG108-15 and SK-N-SH (101). 

Receptors linked to effectors via G proteins A very large number of drugs bind to receptors that are linked by coupling proteins to intracellular or membrane effectors. The best defined examples of this group are the sympathomimetic drugs, which activate or inhibit adenylyl cyclase (formerly called adenylate cyclase) by a multistep process aetivation of the receptor by the drug results in activation of G proteins that either stimulate or inhibit the cyclase. More than 20 types of G proteins have been identified three of the most important are listed in Table 2-2. 

This enzyme is known by two names, adenylate cyclase (EC 4.6.1.1)- its official name from the International Union of Biochemistry and Molecular Biology Nomenclature Committee or its alternative name, adenylyl cyclase. 

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