Cyclase

About: Cyclase is a research topic. Over the lifetime, 10162 publications have been published within this topic receiving 388566 citations.

Hemicyst formation stimulated by cyclic AMP in dog kidney cell line MDCK.

Abstract: Certain epithelial cell lines have morphologic, physiologic, biochemical and pharmacologic characteristics of transporting epithelia from intact organs. In this paper we show that dibutyryl cyclic AMP, 5' AMP, adenosine and cyclic AMP phosphodiesterase inhibitors stimulate hemicyst formation by the dog kidney cell line MDCK. It is suggested that this effect is explained by elevation of intracellular cyclic AMP levels by means of an exogenous non-metabolizable source of cyclic AMP, phosphodiesterase inhibition or adenyl cyclase stimulation. Since hemicyst formation is in part due to transepithelial fluid transport, these findings raise the possibility that this fraction might be modulated by cAMP in an established cell line. We believe that cultured epithelial cells may provide an exploitable model system to investigate at the cellular and subcellular levels, the mechanism by which cyclic AMP modifies water and solute movements across epithelia.

Aminergic receptors in Drosophila melanogaster: responsiveness of adenylate cyclase to putative neurotransmitters.

Abstract: Adenylate cyclase in Drosophila melanogaster heads is stimulated 5-6-fold by low concentrations of octopamine. The octopamine stimulation is inhibited by low concentrations of the alpha-adrenergic ligands phentolamine and dihydroergotamine and of chlorpromazine, but not by low concentrations of the beta-antagonist propranolol and by the alpha-antagonist yohimbine. d-Tubocurarine enhances the octopamine effect. Tyramine, norepinephrine, and epinephrine also stimulate the cyclase, probably via the octopamine receptor. Serotonin and dopamine stimulate Drosophila adenylate cyclase 1.3-1.4-fold; at least the latter putative neurotransmitter seems to interact with a receptor distinct from the octopamine receptor. Prolonged incubation with dopamine in vitro abolishes adenylate cyclase basal activity as well as responsiveness to guanyl nucleotides, NaF, and putative neurotransmitters.

Adenylate cyclases in yeast: a comparison of the genes from Schizosaccharomyces pombe and Saccharomyces cerevisiae.

Abstract: A Schizosaccharomyces pombe gene encoding adenylate cyclase has been cloned by cross-hybridization with the Saccharomyces cerevisiae adenylate cyclase gene. The protein encoded consists of 1692 amino acids and has adenylate cyclase activity that cannot be activated by the Sa. cerevisiae RAS2 protein. Sc. pombe cyclase has a high degree of homology (approximately 60%) with the catalytic domain of Sa. cerevisiae cyclase precisely mapped by a gene-deletion analysis. A 25-40% identity is observed throughout the middle segments of approximately 1000 residues of both cyclases, large parts of which are composed of repetitions of a 23-amino acid motif similar to those found in human glycoproteins, Drosophila chaoptin, and Toll gene product. However, a segment corresponding to the NH2-terminal 620 residues of Sa. cerevisiae cyclase appears lost from Sc. pombe cyclase, and the COOH-terminal 140 residues are not well conserved between the two yeast species. Deletions involving the COOH-terminal residues of Sa. cerevisiae cyclase cause loss of activation by the RAS2 protein. These results suggest that Sc. pombe cyclase may have lost the ability to interact with RAS proteins by the loss of a regulatory site.

Yeast cdc35 mutants are defective in adenylate cyclase and are allelic with cyr1 mutants while CAS1, a new gene, is involved in the regulation of adenylate cyclase.

Abstract: Newly isolated temperature-sensitive cdc35 mutants of Saccharomyces cerevisiae have been characterized. They show the morphology, growth and conjugation characteristics typical of class-A or class-II start mutants. The cdc35 mutation induces a significant decrease of the intracellular cAMP level and produces a thermolabile adenylate cyclase. By classical genetic criteria the CDC35 gene is identical with the structural gene of adenylate cyclase, CYR1. The results of the mutant selection, the kinetics of macromolecule accumulation and the cell-density change of cdc35 mutants at the restrictive temperature, indicate that CDC35 function may not be cell cycle-specific. A new mutation, cas1, was isolated and partially characterized. It mediates the suppression by external cAMP of the unlinked cdc35 mutation. It causes a slight increase of the intracellular cAMP level and has strong effects on the adenylate cyclase activities, especially on the Mg2+ dependent activity. The data suggest that the CAS1 protein is a controlling element of adenylated cyclase. The CAS1 locus is different from the RAS1 and RAS2 loci.