Cyclic AMP and cyclic GMP were released into the growth medium of mycelia of Neurospora crassa wild-type strains St.L.74A and Em5297a and by white collar-1 and white collar-2 mutant strains. After growth for 6 days at 18 degrees C, there were 2.19 (St.L.74A), 5.83 (Em5297a), 1.38 (white collar-1), and 1.10 (white collar-2) nanomoles of cyclic AMP per gram dry weight of mycelia in the growth med...

system of inactivation or degradation of the enzyme. Therefore, after tumor promoter treatment, the level of epidermal ODC would be permanently high and result in polyamine accumula tion, leading to a growing tumor. The role of cyclic nucleotides in the mechanism of induction of ODC by TPA has been studied. In different cell systems and in response to various stimuli, there is a sequential rela...

Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels control cardiac and neuronal rhythmicity. HCN channels contain cyclic nucleotide-binding domain (CNBD) in their C-terminal region linked to the pore-forming transmembrane segment with a C-linker. The C-linker couples the conformational changes caused by the direct binding of cyclic nucleotides to the HCN pore opening. Recent...

To date eleven human PDE (3',5'-cyclic nucleotide phosphodiesterase) families have been identified. Of these, five families contain non-catalytic tandem GAF (cGMP-specific and -stimulated phosphodiesterases, Anabaena adenylate cyclases and Escherichia coli FhlA) domains, GAFa and GAFb, in the N-terminal part of the enzyme. For PDE2A, PDE5A and PDE6 the GAF domains have been shown to bind cGMP w...

The second messenger cyclic nucleotides, cyclic AMP and cyclic GMP, mediate relaxation of airways smooth muscle and suppression of multiple inflammatory cell functions. The intracellular concentrations of these cyclic nucleotides are regulated by a superfamily of phosphodiesterase (PDE) enzymes which break down cAMP and cGMP and, thereby, affect airway tone and inflammation. Theophylline and ot...