CAMP—See Cyclic adenosine monophosphate

If MLCK activates contraction by increasing myosin phosphorylation, then an increase in the activity of myosin light chain phosphatase, MLCP, by decreasing the fraction of myosin which is phosphorylated, should lead to relaxation from the active (contractile) state. Cyclic adenosine monophosphate (AMP) is a strong inhibitor of smooth muscle contraction and it has been suggested that activation of MLCP could result from its phosphorylation via cAMP activated protein kinase (see Figure 5). 

Corey lactol, 4 Cormethasone acetate, 194 Cormethasone acetate, 196 Cortisone, 176, 179 Cortivazol, 191 Cotinine, 235 Curare, 162 Cgclacillin, 439 Cgclazocine, 327 Cyclic adenosine monophosphate, see CAMP Cgclobendazole, 353 Cyclopropanation, 32, 166, 168, 174. 223, 297 Cgheptamide, 222 Cypenamine, 7 Cyprazepam, 402 Cyprolidol, 31 Cyproquinate, 368 Cyproterone acetate, 166 Cyproximide, 293... 

The activation of adenylyl cyclase enables it to catalyze the conversion of adenosine triphosphate (ATP) to 3 5 -cyclic adenosine monophosphate (cAMP), which in turn can activate a number of enzymes known as kinases. Each kinase phosphorylates a specific protein or proteins. Such phosphorylation reactions are known to be involved in the opening of some calcium channels as well as in the activation of other enzymes. In this system, the receptor is in the membrane with its binding site on the outer surface. The G protein is totally within the membrane while the adenylyl cyclase is within the membrane but projects into the interior of the cell. The cAMP is generated within the cell (see Rgure 10.4). 

Glucagon appears to exert its effects on liver cells by a classic adenyl cyclase-cyclic adenosine monophosphate (cAMP) second messenger system (see Chapter 4).93 Glucagon binds to a specific receptor located on the hepatic cell membrane. This stimulates the activity of the adenyl cyclase enzyme that transforms adeno-... 

Phosphoenolpyruvate carboxykinase is induced. Oxaloacetate produces PEP in a reaction catalyzed by PEPCK. Cytosolic PEPCK is an inducible enzyme, which means that the quantity of the enzyme in the cell increases because of increased transcription of its gene and increased translation of its mRNA. The major inducer is cyclic adenosine monophosphate (cAMP), which is increased by hormones that activate adenylate cyclase. Adenylate cyclase produces cAMP from ATP. Glucagon is the hormone that causes cAMP to rise during fasting, whereas epinephrine acts during exercise or stress. cAMP activates protein kinase A, which phosphorylates a set of specific transcription factors (CREB) that stimulate transcription of the PEPCK gene (see Chapter 16 and Pig. 16.18). Increased synthesis of mRNA for PEPCK results in increased synthesis of the enzyme. Cortisol, the major human glucocorticoid, also induces PEPCK. 

Subsequently, the range of the analytes was expanded by adding cyclic adenosine monophosphate (cAMP), adenosine monophosphate (AMP), and the pyrophosphate anion (PPi) to the DCL sensor. Six independent measurements were performed for each analyte ([nucleotide] = [PPJ = l.OmM). The intensities at five different wavelengths were chosen as the input variables for a LDA (see Glossary in Box 7.1). The resulting score plot is shown in Figure 7.7. The data appear in well-separated groups, which shows that the sensor can easily discriminate the six analytes. 

Activation of the postsynaptic receptor also leads to activation of the enzymes involved m the formation of so-called second messengers (see Box 42 for explanation of this and other terms used m this section). Best-known second messengers are cychc adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP) and cleavage products of phosphatidyh-nositol. These molecules are formed at the cell membrane and migrate into the cell where they affect the activity of other enzymes. 

---