Characterization by two-dimensional peptide mapping of the gamma subunits of Ns and Ni, the regulatory proteins of adenylyl cyclase, and of transducin, the guanine nucleotide-binding protein of rod outer segments of the eye

Ns and Ni, the regulatory proteins affecting adenylyl cyclase, and transducin, the guanine nucleotide-binding protein from rod outer segments of the eye, are structurally and functionally related proteins. Of these, the alpha subunits are between 39 and 42 kDa in mass, beta subunits are all of 35 kDa in mass, and gamma subunits are much smaller, of approximately 5-8 kDa in mass. We compared, by two-dimensional peptide mapping of iodinated peptides, the beta and gamma subunits of human erythrocyte Ns, human erythrocyte Ni, the beta gamma complex derived from purification of bovine brain N proteins, and frog and bovine eye transducins. We found that gamma subunits in human erythrocyte Ns and Ni and in bovine brain beta gamma complex are indistinguishable by this approach. In contrast, gamma subunits associated with frog and bovine transducin differed markedly between each other and from N protein-associated gamma. beta subunits, on the other hand, yielded essentially indistinguishable peptide maps regardless of whether derived from N proteins or from transducin and regardless also of species of origin: human versus bovine versus frog. These results suggest that the gamma subunit may impart functional heterogeneity of this family of proteins which is evident in the N proteins on the one hand and the transducin proteins on the other

Inhibitory effects of the beta-adrenergic receptor agonist zilpaterol on the LPS-induced production of TNF-alpha in vitro and in vivo.

Contains fulltext : 32642.pdf (publisher's version ) (Closed access)In this study the anti-inflammatory properties of zilpaterol, a beta2-adrenergic receptor (AR) agonist specifically developed as a growth promoter in cattle were investigated. Although zilpaterol has a different structure compared with the beta2-AR agonists known to date, it was noted that it was able to bind to both the beta2-AR (Ki = 1.1 x 10(-6)) and the beta1-AR (Ki = 1.0 x 10(-5)). Using lipopolysaccharide (LPS)-exposed U937 macrophages, the production of cyclic adenosine-3',5'-cyclic monophosphate (cAMP) and tumor necrosis factor alpha (TNF-alpha) were investigated. Zilpaterol inhibited TNF-alpha release and induced intracellular cAMP levels in a dose-dependent manner. The inhibition of TNF-alpha release and induction of cAMP production was mainly mediated via the beta2-AR, as indicated by addition of beta1- and beta2-specific antagonists. The effects of zilpaterol were investigated in LPS-treated male Wistar rats after pretreatment with zilpaterol. Zilpaterol dosed at 500 microg/kg body weight reduced the TNF-alpha plasma levels. In conclusion, zilpaterol is a beta2-adrenergic agonist and an inhibitor of TNF-alpha production induced by LPS both in vivo and in vitro

The Identification of Pats1, a Novel Gene Locus Required for Cytokinesis in Dictyostelium discoideum

Here, we describe the identification and characterization of the cytokinesis-deficient mutant cell line 17HG5, which was generated in a restriction enzyme–mediated integration mutagenesis screen designed to isolate genes required for cytokinesis in Dictyostelium discoideum. Phenotypic characterization of the 17HG5 cell line revealed no apparent defects in the global functionality of the actomyosin cytoskeleton except for the observed cytokinesis defect when grown in suspension culture. Plasmid rescue was used to identify the disrupted gene locus (pats1; protein associated with the transduction of signal 1) that caused the cytokinesis defect. Disruption of the pats1 locus was recreated through homologous recombination in several independent cell lines, each recapitulating the cytokinesis-defective phenotype and thereby confirming that this gene locus is important for proper cytokinesis. Sequence data obtained by analysis of the genomic region flanking the inserted restriction enzyme–mediated integration plasmid revealed an 8892-bp genomic open reading frame encoding a 2964-amino-acid protein. The putative pats1 protein contains 3 regulatory domains (RI-phosphatase, RII-GTP–binding, R-III protein kinase), 13 leucine-rich repeats, and 8 WD-40 repeats. These regulatory domains coupled with the protein–protein interacting domains suggest that pats1 is involved in signal transduction during cytokinesis in Dictyostelium