Stimulation and inhibition of adenylyl cyclases mediated by distinct regulatory proteins

Abstract

Adenylyl cyclases are under positive and negative control by guanine nucleotides and hormones. Stimulatory responses are mediated by a guanine nucleotide- and Mg-binding regulatory component (Ns), a protein that has been purified to homogeneity. Inhibitory responses have been hypothesized to be mediated by an analogous regulatory component (Ni) distinct from Ns, but definitive proof for this is lacking and these effects may result from modulation of Ns activity. Recently, Bordetella pertussis toxin has been shown to ADP-ribosylate a peptide that is not part of Ns, and this coincides with attenuation of hormonal inhibition of adenylyl cyclase. We show here that cyc- S49 cells contain a substrate for ADP-ribosylation by pertussis toxin and that the toxin alters GTP dependent inhibition of cyc- adenyl cyclase activity. As cyc- S49 cells do not contain Ns by several criteria, we conclude that Ni is a distinct and separate regulatory component of adenylyl cyclase.

The adenosine receptor‐mediated inhibition of noradrenaline release possibly involves a N‐protein and is increased by α2‐autoreceptor blockade

“…The enhancement of noradrenaline release by NEM (Figure 1 a) is probably due to a partial inactivation of the autoinhibitory feedback system at the level of a regulatory N-protein (Allgaier et al, 1986). Similar results have been obtained in experiments with isletactivating protein, pertussis toxin (Allgaier et al, 1985), which activates N, of adenylate cyclase as well as No by ADP-ribosylation (Hildebrandt et al, 1983;Sternweis & Robishaw, 1984).…”

“…ADP-ribosylation of the a-subunit of Ni caused by islet-activating protein (pertussis toxin) diminished or even abolished receptor-coupled inhibition of aden-'Author for correspondence. ylate cyclase (Hildebrandt et al, 1983;Murayama & Ui, 1983) and decreased, like guanine nucleotides (Rodbell, 1980), the agonist affinity for inhibitory receptors by uncoupling Ni from its receptor (Kurose et al, 1983;Boyer et al, 1984;Cote et al, 1984;Nomura et al, 1985). These observations are similar to those obtained with the SH-reagent N-ethylmaleimide (NEM).…”

Immunogenic calreticulin exposure occurs through a phylogenetically conserved stress pathway involving the chemokine CXCL8

“…The a factor signals through a G protein-coupled receptor (GPCR). 30 We therefore evaluated the capacity of the pertussis toxin (PTX), a large-spectrum inhibitor of mammalian GPCRs, 31 to inhibit MTX-induced CRT exposure in cervical carcinoma HeLa cells. PTX was indeed highly efficient at suppressing CRT exposure by HeLa cells responding to MTX or UVC light, as determined by surface immunostaining and flow cytometry or fluorescence microscopy (Figures 2a and b).…”

The same mutation in Gsα and transducin α reveals behavioral differences between these highly homologous G protein α-subunits

“…Radioisotopes [␣- 32 I-CYP) was from NENPerkinElmer. Bovine gamma globulin, (Ϫ)isoproterenol, and PGE1 were from Sigma-Aldrich; polyethyleneglycol 6000 was from Calbiochem, and guanine nucleotides were from Boehringer-Ingelheim.…”