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Biomedical subjects

S Natori

Publications and source records attributed to S Natori.

At least 253 records · Page 14Linked to original sources
PubMed1986

Transcription factor(s) of Ehrlich ascites tumor cells having affinity to the 'TATA' box and a further upstream region of the adenovirus 2 major late gene.

A fraction containing a transcription factor(s) of RNA polymerase II was prepared from a nuclear lysate of Ehrlich ascites tumor cells and its binding to a promoter region of the adenovirus 2 major late gene was examined. Results showed that this fraction contained a factor(s) binding to two distinct regions: a region including the 'TATA' box and another region further upstream. The upstream protected region was different from that reported to be protected by a HeLa cell factor, suggesting species specificity of transcription factor(s) in DNA binding.

Adenoviruses, Human↗
PubMed1986

Effects of chaetoglobosin J on the G-F transformation of actin.

It was shown that substoichiometric concentrations of chaetoglobosin J, one of the fungal metabolites belonging to cytochalasins, inhibited the elongation at the barbed end of an actin filament. Stoichiometric concentrations of chaetoglobosin J decreased both the rate and the extent of actin polymerization in the presence of 75 mM KCl, 0.2 mM ATP and 10 mM Tris-HCl buffer at pH 8.0 and 25 degrees C. In contrast, stoichiometric concentrations of cytochalasin D accelerated actin polymerization. Chaetoglobosin J slowly depolymerized F-actin to G-actin until an equilibrium was reached. Analyses by a number of different methods showed the increase of monomer concentration at equilibrium to depend on chaetoglobosin J concentrations. F-actin under the influence of stoichiometric concentrations of chaetoglobosin J only slightly activated the Mg2+-enhanced ATPase activity of myosin at low ionic strength. It is suggested that when the structure of the chaetoglobosin-affected actin filaments is modified, the equilibrium is shifted to the monomer side, and the interaction with myosin is weakened.

Actins↗
PubMed1986

Molecular cloning of a cDNA and assignment of the C-terminal of sarcotoxin IA, a potent antibacterial protein of Sarcophaga peregrina.

A previous paper described the complete amino acid sequences of sarcotoxins IA, IB and IC, which are a group of potent antibacterial proteins with almost identical primary structures produced by Sarcophaga peregrina (fleshfly) larvae [Okada & Natori (1985) J. Biol. Chem. 260, 7174-7177]. The present paper describes the cDNA cloning and complete nucleotide sequencing of a cDNA clone for sarcotoxin IA. The C-terminal amino acid residue of sarcotoxin IA deduced from the nucleotide sequence was glycine, whereas it was found to be arginine by amino acid sequencing of purified sarcotoxin IA. Analysis of the elution profiles on h.p.l.c. of the synthetic derivatives of sarcotoxin IA showed that the C-terminal amino acid residue of authentic sarcotoxin IA is amidated arginine, which is probably produced by enzymic cleavage of terminal glycine.

Amino Acid Sequence↗
PubMed1986

In vitro transcription of a chromatin-like complex of major core protein VII and DNA of adenovirus serotype 2.

Major core protein VII of adenovirus serotype 2 (Ad2) is thought to play a role as a histone octamer in eukaryotic cells. We compared the template activity of the VII-DNA complex formed in vitro with that of protein-free DNA. Hybridization assay of in vitro transcripts showed that transcription from regions located in the middle of Ad2 DNA decreased when Ad2 DNA formed a complex with VII. This suggests that the chromatin structure plays a role in regulation of transcription of the adenovirus genome.

Adenoviridae↗
PubMed1986

Homologies of nucleotide sequences in the 5'-end regions of two developmentally regulated genes of Sarcophaga peregrina.

In the previous paper we demonstrated that the storage protein gene and 25-kDa protein gene are expressed sequentially in the fat body of middle third-instar Sarcophaga peregrina larvae. In this paper, we showed that the expressions of these two genes are regulated at the transcriptional level, and searched for homologous nucleotide sequences in the two genes in the vicinity of their 5'-ends, assuming that these two genes are regulated by a common mechanism. We selected 9 homologous sequences and found that most of them were distributed in two clusters located between positions -400 and +1. We identified an SV40 enhancer core segment-like sequence in the nontranslated region of the first exons of both genes, which might explain the efficient transcriptions of these two genes.

Animals↗
PubMed1986

Analysis of the DNase I-hypersensitive site of a developmentally regulated 25-kDa protein gene of Sarcophaga peregrina.

Change in chromatin structure of a developmentally regulated gene of Sarcophaga peregrina (flesh fly) during development was investigated. This gene (25-kDa protein gene) was specifically activated in the fat body, but not the hemocytes of larvae in the middle of the third instar. The mRNA level in the fat body decreased thereafter, reaching one-fifth of the maximum level in the late third instar to early pupal stage. In the chromatin of fat body nuclei, a DNase I-hypersensitive site was found about 300 base pairs upstream from the transcription initiation site of the 25-kDa protein gene. This DNase I-hypersensitive site appeared before activation of the 25-kDa protein gene, and it was conserved until the late third instar, but disappeared in the early pupal stage. Since activity of the 25-kDa protein gene decreases significantly in the early pupal stage, it is likely that disappearance of this DNase I-hypersensitive site coincides with inactivation of the 25-kDa protein gene.

Animals↗
PubMed1986

Identification of 30-kDa fat body protein of Sarcophaga peregrina larvae selectively phosphorylated in the presence of 20-hydroxyecdysone as ribosomal protein S6.

Previously, we showed that 20-hydroxyecdysone induces selective phosphorylation of a fat body protein of Sarcophaga peregrina with a molecular mass of about 30,000 (30-kDa protein) (Itoh, K., Ueno, K., & Natori, S. (1985) Biochem. J. 227, 683-688). This paper describes the identification of this 30-kDa protein. From the electrophoretic profile of 40S ribosomal proteins on two-dimensional polyacrylamide gel electrophoresis, the 30-kDa protein was identified as S6.

Adipose Tissue↗
PubMed1986

Purification of a cytotoxic protein produced by the murine macrophage-like cell line J774.1 in response to Sarcophaga lectin.

A tumor specific cytotoxic protein produced by the murine macrophage-like cell line J774.1 in response to stimulation with Sarcophaga lectin was purified to homogeneity in three steps from the culture medium. This cytotoxin, named tumor killing factor (TKF), was a protein with a molecular weight of 15,000, and aggregated forming an oligomer with a molecular weight of 48,000. Its amino acid composition was similar to that of human TNF. Purified TKF had a significant effect on transplanted murine ascites tumor sarcoma 180. The biological significance of TKF in terms of ontogeny is discussed from the view point of developmental biology.

Amino Acids↗
PubMed1986

Participation of common surface receptor(s) in the activation of murine macrophages by Sarcophaga lectin and wheat germ agglutinin.

Mouse peritoneal macrophage surface proteins which bind Sarcophaga lectin were studied. Two major binding proteins with molecular masses of 170 and 110 kDa were identified. Sarcophaga lectin and wheat germ agglutinin were found to share common binding proteins for activating macrophages, although their hapten sugars are different. Antibody raised against the Sarcophaga lectin-binding proteins inhibited both the production of tumor-specific cytotoxic protein by the macrophage-like cell line J774.1 cells and the lectin-dependent macrophage-mediated cytotoxic reaction induced by Sarcophaga lectin or wheat germ agglutinin. Thus the 170-kDa and/or 110-kDa protein is important in activation of macrophages.

Animals↗
PubMed1985

Cloning and sequencing of cDNA of Sarcophaga peregrina humoral lectin induced on injury of the body wall.

A previous paper described the purification of a lectin induced in the hemolymph of larvae of Sarcophaga peregrina (flesh-fly) on injury of their body wall (Komano, H., Mizuno, D., and Natori, S. (1980) J. Biol. Chem. 255, 2919-2924). This paper describes cDNA cloning and the complete nucleotide sequence of the gene for Sarcophaga lectin. Although active lectin consists of alpha and beta subunits in a molar ratio of 2:1, the fat body of injured larvae was found to contain only mRNA for the alpha subunit, suggesting that these two subunits are derived from a common gene and that the alpha subunit is converted to the beta subunit post-translationally. The alpha subunit was found to consist of 260 amino acid residues with an additional signal sequence of 19 or 23 amino acid residues.

Amino Acid Sequence↗
PubMed1985

Phosphorylation of S-II is not affected by inhibitors of RNA synthesis.

S-II is an essential factor for RNA polymerase II-mediated transcription. A phosphorylated form of S-II, termed S-II has been shown to be present in cells at half the concentration of S-II. In studies on the role of phosphorylation and dephosphorylation of S-II in transcription, the possibility that phosphorylation of S-II is coupled with transcription in vivo was investigated. The phosphorylation of S-II was measured in mouse L cells cultured with two typical inhibitors of RNA synthesis. Neither of these inhibitors, 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) and actinomycin D, affected the phosphorylation of S-II under conditions where 75 to 98% of RNA synthesis was inhibited at the initiation and elongation step, respectively. These results indicate that the phosphorylation of S-II and transcription are independent processes.

Animals↗
PubMed1985

Ionophore activity of sarcotoxin I, a bactericidal protein of Sarcophaga peregrina.

When Escherichia coli was treated with sarcotoxin I, a potent bactericidal protein of Sarcophaga peregrina (fleshfly), K+ inside of the cells leaked out rapidly and the ATP pool of the cells rapidly decreased. These results suggested that the bactericidal effect of sarcotoxin I was due to its ionophore activity, and that it blocked the generation of ATP by inhibiting formation of the proton gradient essential for oxidative phosphorylation. This was confirmed by use of an uncA mutant, which was much less susceptible than the wild-type strain to sarcotoxin I under fixed ionic conditions.

Adenosine Triphosphate↗