Adenylate cyclase of rat adipocyte membranes exhibited dual responses in a strictly GTP-dependent manner; an activation took place in the presence of certain receptor agonists such as isoproterenol or secretin, whereas an inhibitory phase was observed with other agonists such as prostaglandin E1 or purine-modified adenosine as well as with the stimulatory agonists at higher GTP concentrations. ...

When WBC264-9C cells are preincubated with pertussis toxin, chemotaxis is inhibited and ADP-ribosylation of a membrane protein with a subunit Mr 41,000 is observed. Both the inhibition of chemotaxis and the ADP-ribosylation by pertussis toxin display a similar time lag, temperature dependence, and pertussis toxin-concentration dependence. Although the inhibition of chemotaxis and the ADP-ribosy...

The regulatory component (G/F) of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] from rabbit liver plasma membranes has been purified essentially to homogeneity. The purification was accomplished by three chromatographic procedures in sodium cholate-containing solutions, followed by three steps in Lubrol-containing solutions. The specific activity of G/F was enriched 2000-f...

Adenylate cyclase of the membrane-rich fraction of 24-h cultured islets was inhibited by epinephrine via alpha-adrenergic receptors. Epinephrine was inhibitory only when the enzyme was activated by GTP; the degree of inhibition was highly proportional to the degree of GTP activation. Adenylate cyclase of islets cultured with islet-activating protein (IAP), one of the pertussis toxins, was less ...

Chronic exposure of sheep adipose tissue to growth hormone (GH) in vitro decreases the ability of the adenosine analogue, N6-phenylisopropyladenosine (PIA), to inhibit isoprenaline-stimulated lipolysis by a mechanism which is dependent on both gene transcription and protein serine/threonine phosphorylation. The inhibition is not due to a change in ligand binding to the adenosine receptor, the a...

Bordetellae, pathogenic to mammals, produce an immunomodulatory adenylate cyclase toxin-hemolysin (CyaA, ACT or AC-Hly) that enables them to overcome the innate immune defense of the host. CyaA subverts host phagocytic cells by an orchestrated action of its functional domains, where an extremely catalytically active adenylyl cyclase enzyme is delivered into phagocyte cytosol by a pore-forming r...

NAD is a necessary cofactor for the activation of adenylate cyclase (ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1) by cholera toxin. Lysates of certain types of cell that hydrolyze their endogenous store of NAD after cell disruption respond poorly or not at all to cholera toxin. Lysates of pigeon erythrocytes, which lack enzymes that degrade NAD, provide a convenient and reproducible system ...

Adenylate cyclase toxin (ACT or CyaA) plays a crucial role in respiratory tract colonization and virulence of the whooping cough causative bacterium Bordetella pertussis Secreted as soluble protein, it targets myeloid cells expressing the CD11b/CD18 integrin and on delivery of its N-terminal adenylate cyclase catalytic domain (AC domain) into the cytosol, generates uncontrolled toxic levels of ...

The molecular mechanisms and forces involved in the translocation of bacterial toxins into host cells are still a matter intense research. adenylate cyclase (CyaA) toxin from Bordetella pertussis displays unique intoxication pathway which its catalytic domain is directly translocated across target cell membranes. CyaA region contains segment, P454 (residues 454–484), exhibits membrane-active pr...