Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.6.1.1 (adenylate cyclase)
 19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. FMRFamide and the Catch relaxing peptide (CARP) at 0.01-0.1 nM modulate acetylcholine (ACh) induced currents of identified neurons of Helix aspersa, but have no direct effect on membrane current and conductivity. 2. Both FMRFamide and CARP noncompetitively inhibit ACh Cl- responses while having either no effect or increasing ACh Na+/K+ response. 3. The inhibitory effect of FMRFamide and CARP on the ACh Cl- response was eliminated following pretreatment with forskolin (20 microM), an activator of adenylate cyclase. 4. Ascaris peptide (ASC) and a synthetic CARP analogue NORL-CARP, in which the amino acid methionine is replaced by either leucine or norleucine, at 1-10 microM, showed no effect on responses to ACh. 5. FMRFamide and CARP, at 10 nM, increased cAMP levels to 240% and 148% respectively above resting basal cAMP levels, while ASC and NORL-CARP had no significant effective. 6. Our results suggest that FMRFamide and CARP, in low concentrations, modulate ACh responses of Helix neurons, possibly through changes in cAMP levels. They also indicate the importance of the presence of methionine in these neuroactive peptides.
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PMID:Low concentrations of neuroactive peptides modulate cholinergic transmission and cyclic AMP levels in Helix aspersa. 133 59

1. Catch is a mechanism found in many molluscan smooth muscles in which tension is maintained at relatively low energy cost. 2. Paramyosin forms the core of thick filaments. In catch muscle paramyosin concentrations are high and the thick filaments are relatively long. 3. The mechanism of catch is not understood, but the consensus is that tension during catch is borne by slowly-cycling cross-bridge attachments to actin. 4. Stimulation by acetylcholine increases intracellular Ca2+ and initiates a contraction characterized by a relatively rapid cross-bridge cycling. Reduction of Ca2+ can lead to relaxation or catch. Relaxation occurs only when a second neurotransmitter, serotonin, is present. 5. The catch state is released by serotonin, via activation of adenylate cyclase, increased levels of cAMP and phosphorylation of one or more contractile proteins, possibly paramyosin. Other targets for phosphorylation are discussed. 6. The contractile cycle of catch muscles, therefore, is controlled by both Ca2+ and cAMP.
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PMID:Paramyosin and the catch mechanism. 222 69