1. The activities of the enzymes involved in the metabolism of cyclic nucleotides were studied in sarcolemma prepared front guinea-pig heart ventricle; the enzyme activities reported here were linear under the assay conditions. 2. Adenylate cyclase was maximally activated by 3mM-NaF; NaF increased the Km for ATP (from 0.042 to 0.19 mM) but decreased the Ka for Mg2+ (from 2.33 to 0.9 mM). In the...

OBJECTIVE It has been assumed that some behavioral changes associated with repeated exposure to dopaminergic psychostimulant drugs might be explained by changes in activity of dopamine receptors, including the dopamine D(1) receptor, which is linked by a stimulatory G protein to the effector enzyme adenylyl cyclase. To establish whether dopamine D(1) receptor function might be altered in human ...

Soluble guanylyl cyclase (sGC) is activated by nitric oxide (NO) and generates the second messenger cyclic GMP (cGMP). Recently, purified sGC α1β1 has been shown to additionally generate the cyclic pyrimidine nucleotides cCMP and cUMP. However, since cyclic pyrimidine nucleotide formation occurred only the presence of Mn(2+) but not Mg(2+), the physiological relevance of these in vitro findings...

The adrenal chromaffin cells synthesize and release catecholamine (mostly epinephrine and norepinephrine) and different peptides, such as the neuropeptide Y (NPY). NPY stimulates catecholamine release through NPY Y1 receptor in mouse chromaffin cells. The aim of our study was to determine the intracellular signaling events coupled to NPY Y1 receptor activation that lead to stimulation of catech...

C-type natriuretic peptide (CNP) binds and activates the transmembrane guanylyl cyclase B receptor (NPR-B), which decreases vascular tone and inhibits cell proliferation and migration. In contrast, the bioactive lipid sphingosine-1-phosphate (S1P) elicits the opposite physiological effects. Here, we demonstrate a potent acute inhibitory effect of S1P on NPR-B activity in NIH3T3 fibroblasts and ...

Uroguanylin, which serves as an endogenous ligand of guanylyl cyclase C, is initially secreted in the form of a precursor, prouroguanylin. The N-terminal region of prouroguanylin interacts with the mature portion of prouroguanylin during the folding pathway. Here, a preliminary X-ray crystallographic study of prouroguanylin is presented. Prouroguanylin was refolded, purified and crystallized us...