Adenylate cyclase can be resolved into at least two proteins, a thermolabile, N-ethylmaleimide-sensitive component and a second protein (or proteins) that is more stable to either of these treatments. Neither component by itself catalyzes the formation of cyclic AMP using MgATP as substrate. However, mixture of the two reconstitutes MgATP-dependent fluoride- and guanyl-5'-yl imidodiphosphate (G...

To evaluate a possible role for adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] and adenosine 3':5'-cyclic monophosphate in the secretion of endolymph, we studied the effect of an intra-scala media injection of purified cholera toxin (an adenylate cyclase stimulant) on cochlear endolymph volume, endolymphatic potential, and endolymphatic Na and K concentrations.

The present study was undertaken to localize adenylate cyclase activity in salivary glands by cytochemical means. For the study, serous parotid glands and mixed sublingual glands of the rat were used. Pieces of the fixed glands were incubated with adenosine triphosphate (ATP) or adenylyl-imidodiphosphate (AMP-PNP) as substrate: inorganic pyrophosphate or PNP liberated upon the action of adenyla...

BACKGROUND We measured the content and activities of components of the beta-adrenergic receptor-G protein-adenylate cyclase complex and adrenergic neurotransmitter levels in left and right ventricular myocardial preparations derived from 77 end-stage failing human hearts from patients with idiopathic dilated cardiomyopathy (IDC) or ischemic dilated cardiomyopathy (ISCDC). METHODS AND RESULTS ...

Cholera toxin treatment (up to 1 microgram/ml, 16 h) of neuroblastoma x glioma hybrid NG108-15 cells produced a decrease of some 35% in both delta opioid receptor-mediated stimulation of high-affinity GTPase activity and inhibition of forskolin-amplified adenylate cyclase. Coincident with these decreases was a down-regulation of some 35% in the delta opioid receptor population. A similar patter...

Recent evidence suggests that serotonin (5-HT) and a neuropeptide, small cardioactive peptideB (SCPB), exert parallel modulatory actions on neuronal and muscular function in Aplysia via changes in the levels of cAMP. We have examined the effects of both of these neurotransmitters on the adenylate cyclase activity in membrane homogenates of pleural ganglia. The results indicated that 5-HT and SC...

The molecular weight of NaF-activated, Triton N-101-solubilized adenylate cyclase from bovine thyroid membranes has been measured by a combination of sucrose density centrifugation and gel exclusion chromatography. The physical parameters are: sedimentation coefficient, 6.6 S; Stokes radium 41 A; partial specific volume, 0.75 ml/g; molecular weight, 119,000. This is in contrast to the molecular...

A subcellular fraction prepared from rat kidney medulla contained vasopressin-sensitive adenylate cyclase and vasopressin binding sites. Vasopressin stimulation resulted in an increase in the maximal velocity of the reaction with no change in the apparent K, for ATP. A maximum activation ratio (5 to 10) was obtained at low Mg2+ concentration (0.75 mM) and pH 7.4. The apparent Km for vasopressin...

Address reprint requests to Dr. Galant, Memorial Hospital Medical Center of Long Beach, Calif. Received for publication 12 August 1980 and in revised form 23 March 1981. group to include agonist binding, receptor-adenylate cyclase coupling, intrinsic adenylate cyclase activity, and catecholamine metabolism may help determine the basic cause of beta adrenergic hyporesponsiveness in both CFH and CF.