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Volume 113 (1993)
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Volume 113, Issue 5
Displaying 1-20 of 20 articles from this issue
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Nobuko Iritani, Hitomi Fukuda, Yohko Matsumura1993 Volume 113 Issue 5 Pages 519-525
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSThe time courses and the regulation of lipogenic enzyme gene expression during development after birth have been investigated. The mRNA concentrations and activities of liver lipogenic enzymes (acetyl-CoA carboxylase, fatty acid synthase, malic enzyme, glucose-6-phosphate dehydrogenase, and ATP-citrate lyase) were very low in all the suckling rats, regardless of dietary fat of the mothers. After weaning to the same diet as the mothers, the mRNA and enzyme levels were greatly increased by the fat-free or hydrogenated fat diet but not so greatly increased by the corn or fish oil diet. The mRNA concentrations of all the groups reached maximum at 4-6 weeks old and then decreased, usually to 40-60% of the maximal levels. It appeared that the gene expression after weaning is subject to strong nutritional regulation, as well as developmental regulation. The plasma levels of triiodoth-yronine and insulin were low during suckling. Malic enzyme mRNA level was increased by triiodothyronine treatment even during suckling, but the absolute increase was much less than after weaning. Thus, the gene expression of lipogenic enzymes during suckling appeared to be suppressed by nutritional and hormonal regulation, or may not be sufficiently developed. On the other hand, the hepatic triacylglycerol levels were increased slightly at 2 weeks old and greatly at 3 weeks. As the gene expression of lipogenic enzymes was still low at that time, the major triacylglycerols appear to be obtained from milk and accumulated in preparation for weaning.View full abstractDownload PDF (2038K) -
Senarath B. P. Athauda, Hideo Arakawa, Masaaki Nishigai, Takayuki Taka ...1993 Volume 113 Issue 5 Pages 526-530
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSThe activity of cathepsin E (Mr_??_80K), a dimeric aspartic proteinase with two active sites per molecule, toward a protein substrate (reduced and carboxymethylated ribonuclease A) was shown to be completely inhibited by α2-macroglobulin (α2M) at pH 5.5. On the other hand, the activity toward a peptide substrate (oxidized insulin B chain) was scarcely inhibited. Under these conditions, cathepsin E cleaved α2M at the Phe684-Tyr685 bond in the bait region sequence, resulting in a drastic conformational change (from a doughnut to an H shape) in the inhibitor as revealed by electron microscopy, and was non-covalently trapped by α2M in an approximate molar ratio (enzyme :α2M) of 2:1.View full abstractDownload PDF (1759K) -
Izumi Hayashi, Sachiko Oh-ishi1993 Volume 113 Issue 5 Pages 531-537
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSTo clarify the mechanism of plasma kininogen deficiency of Brown Norway Katholiek strain (B/N-Katholiek) rats, we compared synthesis and secretion of kininogens by primary cultures of hepatocytes from B/N-Katholiek and B/N-Kitasato (normal strain) rats. Pulse-and-chase experiments using [35S] methionine demonstrated that kininogen antigens with molecular masses of 100 and 66 kDa, corresponding to high- and lowmolecular-weight kininogens (HK and LK), respectively, were detected in the hepatocytes of both strains. These proteins were then processed to 108- and 71- kDa forms, respectively, and secreted by the normal hepatocytes, while the latter forms were hardly secreted in the culture media of the deficient hepatocytes. However in the deficient cells, 100- and 66-kDa forms were accumulated, but 108- and 71-kDa bands were faint. A subcellular fractionation study showed that a relatively higher amount of the kininogen antigens was present in the lysosomal fraction of B/N-Katholiek hepatocytes than in that of B/N-Kitasato hepatocytes. From these results we postulate the cause of the secretion defect of B/N-Katholiek liver to be as follows. (i) B/N-Katholiek liver could synthesize the mature secretable forms of HK and LK, but they are too rapidly transported to the lysosomes, or (ii) the mature forms in B/N-Katholiek hepatocytes might be synthesized much more slowly than those in the normal cells. T-Kininogen was normally synthesized and secreted by the hepatocytes of B/N-Katholiek, suggesting that the secretion defect could be limited to HK and LK, at a common site.View full abstractDownload PDF (4341K) -
Shigeo Yamamoto, Noriyuki Okujo, Yasuhiro Fujita, Miki Saito, Takashi ...1993 Volume 113 Issue 5 Pages 538-544
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSFrom low-iron cultures of Vibrio fluvialis AQ 0012, two new compounds with siderophore activity were purified by XAD-7 adsorption followed by preparative TLC. Norspermidine and 2, 3-dihydroxybenzoic acid were identified as constituents common to both compounds by GC-MS analyses of their acid hydrolytic products. In addition, L-threonine was identified in the hydrolysate of one compound, named fluvibactin. Based on high magnetic NMR analyses, the structure of fluvibactin was established as N4- [2-(2, 3-dihydroxyphenyl)-trans-5-methyl-2-oxazoline-4-yl] carboxy-N1, N7- bis-(2, 3-dihydroxybenzoyl)-norspermidine, and that of the other compound as N1, N7- bis-(2, 3-dihydroxybenzoyl)-norspermidine. The structures were supported by fast atom bombardment mass spectrometry. Both of the purified compounds restored growth inhibition of the producer strain and V. cholerae Non-O1 induced by ethylenediamine di-(o-hydroxyphenylacetic acid), a potent synthetic chelating agent of ferric iron.View full abstractDownload PDF (2603K) -
Noriko M. Tsuji, Jun-ichi Kurisaki, Koko Mizumachi1993 Volume 113 Issue 5 Pages 545-548
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSBovine β-lactoglobulin (β-LG) specific T cell clones, H1.1, 5G, 2.11G, and 6.11G were established from BALB/c mice and characterized. Surface phenotypes of clones were Thy1+, CD3+, CD4+, and CD8-. All clones recognize β-LG in a I-Ad restricted manner. The T cell determinant region for H1.1 and 5G was identified as residues 42-56 of β-LG by proliferation assay with overlapping synthetic peptides covering the entire sequence of β-LG. The T cell determinant region for H1.1 was further delimited to residues 43-52 by using analog peptides. Previously we analyzed the T cell determinant regions of β-LG in BALB/c, C3H/He, and C57BL/6 mouse by polyclonal T cell proliferation assay and reported that residues 42-56 of β-LG constitute one of the major T cell determinants in BALB/c mice. Specificities of 2.11G and 6.11G were not identified by these synthetic peptides. Although reduction of disulfide bonds and CNBr cleavage of β-LG did not affect the antigen recognition by 2.11G and 6.11G, tryptic degradation of the protein caused a clearer decrease of response in 6.11G than in 2.11G.View full abstractDownload PDF (1363K) -
Nobuhiro Suzuki, Masataka Harada, Chieko Kitada, Shoichi Ohkubo, Hirok ...1993 Volume 113 Issue 5 Pages 549-556
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSSensitive and specific two-side enzyme immunoassays (two-site EIAs) for pituitary adenylate cyclase activating polypeptides, PACAP38, and PACAP27, have been established using six monoclonal antibodies against PACAP38, and a rabbit antibody against a C-terminal portion of PACAP27. In extracts of rat hypothalamus, these EIAs detected not only PACAP38 and PACAP27 but also an immunoreactive (ir-) PACAP lacking an epitope of a monoclonal antibody, PA-1C, which recognizes the C-terminal portion of PACAP38. By the use of these EIAs, it was found that one of the human neuroblastoma cell lines, IMR-32, produced ir-PACAP. In reverse-phase (RP-)HPLC, intracellular and extracellular ir-PACAPs were separated into two peaks, of which one was eluted at a position close to that of PACAP38 and the other in rather hydrophobic fractions. Those ir-PACAPs also lacked PA-1C epitope of PACAP38. SDS-PAGE and immunoblot analysis of the two peaks of the RP-HPLC indicated that they consisted of several components including those with apparent molecular weights of 6.5 k and 10 k for the first peak ir-PACAP, and 14 k and 20 k for the second peak ir-PACAP. These results indicate that IMR-32 produces a precursor of PACAP and related peptides generated in various processing steps. Although the significance of the modification in the C-terminus of PACAP38 is unknown, IMR-32 may be a cell line useful for studying the regulation of the biosynthesis of PACAP.View full abstractDownload PDF (1958K) -
Rakesh Kumar Tyagi, Kasturi Datta1993 Volume 113 Issue 5 Pages 557-562
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSA specific rabbit antibody was prepared against rat kidney mitochondrial L-alanine: 4, 5-dioxovalerate transaminase, which is one of the two enzymes catalyzing the synthesis of δ-aminolevulinic acid in the heme biosynthetic pathway. Total polyadenylated RNA isolated from rat kidney was translated in vitro using rabbit reticulocyte cell-free translation system, and L-alanine:4, 5-dioxovalerate transaminase was estimated by indirect immunoprecipitation to represent 0.85% of the total translation product. When the total in vitro translated product was incubated with homologous kidney mitochondria, 59% of the [35S] methionine labeled enzyme was translocated into the mitochondria where it was no longer accessible to externally added protease. In relation to total protein translocation, the translocation of L-alanine:4, 5-dioxovalerate transaminase remained unaltered by addition of hemin up to 50 μM. These results show that, unlike the other enzyme of the heme biosynthetic pathway (δ-aminolevulinic acid synthetase), this enzyme is not under tight control by heme, but nonetheless, functions as an important source to maintain a housekeeping level of δ-aminolevulinic acid.View full abstractDownload PDF (3454K) -
Ma Begoña Ruiz-Larrea, Ma Jesús Garrido, Mercedes Lacort ...1993 Volume 113 Issue 5 Pages 563-567
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSGlutathione plays an important role in the intracellular protection against oxidative stress and damage in the liver. It is generally assumed that the toxic potential of estrogens is linked to reactive metabolites generated during their enzymatic oxidation in hepatic microsomes. In the present study, the effects of pharmacological doses of estradiol on glutathione metabolism using isolated rat hepatocytes are described. Estradiol (0.1-1.5 mM) produced a dose-dependent depletion of cellular reduced glutathione (GSH), whereas it did not alter the glutathione disulfide (GSSG) excretion into the medium. The viability of cells exposed to the estrogen did not change even when conditions of exacerbated toxicity (addition of either 1 mM diethylmaleimide or 30 μM dicoumarol) were used. In addition, estradiol was shown to exert protective effects against the spontaneous lipid peroxidation in liver cells. In rat liver microsomes, estradiol (5-50 μM) significantly interacted with GSH only when an NADPH-regenerating system was incorporated into the medium.View full abstractDownload PDF (476K) -
Hiromitsu Tanaka, Naoki Goshima, Kyoko Kohno, Yasunobu Kano, Fumio Ima ...1993 Volume 113 Issue 5 Pages 568-572
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSThe interactions of three forms of HU dimer from Escherichia coli with DNA were compared. The complexes formed between HU and short DNA fragments (35 to 132 bp), uncurved oligodeoxyribonucleotide (oligo) with and without 5-bp deoxyriboadenosine (dA) stretches and curved oligo with 5-bp dA stretches, were analyzed by the gel retardation technique. The binding of HU homodimers to the DNA was less efficient than that of HU heterodimer, and the HU-1 homodimer had lower DNA-binding capacity than the HU-2 homodimer. The equilibrium dissociation constant (KD) for DNA of the HU-1 homodimer was 3 times that of the HU heterodimer. The HU dimers had two- to fourfold higher affinity for DNA duplexes containing 5-bp dA stretches, particularly for curved DNA. The binding of HU heterodimer to the DNA was inhibited more by the curved DNA competitor than the uncurved DNA competitor without dA stretches.View full abstractDownload PDF (3868K) -
Satoko Izawa, Yuki Sakai-Tomita, Keisuke Kinomura, Sadaya Kitazawa, Ma ...1993 Volume 113 Issue 5 Pages 573-576
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSWe synthesized a series of non-ionic detergents, alkyl thiomaltosides, and investigated their properties and usefulness. We solubilized membrane proteins of Vibrio parahaemolyticus using the detergents. With octyl thiomaltoside, nonyl thiomaltoside, decyl thiomaltoside, or undecyl thiomaltoside, we observed satisfactory solubilization of the membrane proteins. Alkyl thiomaltosides possessing longer alkyl chains showed better solubilization than ones possessing shorter chains. H+-translocating ATPase (F0F1), which is localized in the cytoplasmic membrane (inner membrane), was solubilized with the detergents, and the solubilized enzyme showed much higher specific activity than that solubilized with octyl glucoside or heptyl thioglucoside, other useful non-ionic detergents. 5'-Nucleotidase, which seems to be an outer membrane protein, was also efficiently solubilized with the alkyl thiomaltosides. Membrane proteins of Escherichia coli were also efficiently solubilized with the detergents. Octyl thiomaltoside and nonyl thiomaltoside were removed fairly rapidly on dialysis. Decyl thiomaltoside was removed slowly, and undecyl thiomaltoside and dodecyl thiomaltoside were difficult to remove by dialysis.View full abstractDownload PDF (465K) -
Ronald J. A. Wanders, Simone W. Denis, Georges Dacremont1993 Volume 113 Issue 5 Pages 577-582
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSWe have studied the substrate specificity of the inducible (acyl-CoA oxidase I) and non-inducible (acyl-CoA oxidase II) oxidases in peroxisome-enriched fractions from rat kidney. The two oxidases were separated by means of ion-exchange chromatography and shown to accept a variety of acyl-CoA esters as substrates, including lignoceroyl-CoA, palmitoyl-CoA, lauroyl-CoA, caproyl-CoA, and trimethyltridecanoyl-CoA. Glutaryl-CoA was found to react exclusively with the inducible enzyme, and pristanoyl-CoA exclusively with the non-inducible enzyme. We conclude that under normal non-induced conditions both acyl-CoA oxidase I and II contribute to the oxidation of the various acyl-CoA esters with the exception of pristanoyl-CoA and glutaryl-CoA, although the extent to which each enzyme contributes to the oxidation was found to differ between the various acyl-CoA esters.View full abstractDownload PDF (647K) -
Isamu Kameshita, Hitoshi Fujisawa1993 Volume 113 Issue 5 Pages 583-590
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSCalmodulin-dependent protein kinase IV from rat cerebral cortex undergoes autophosphorylation in response to Ca2+ and calmodulin, resulting in its marked enzymatic activation. Autophosphorylation occurred at several sites on CaM-kinase IV, depending upon the enzyme concentration. Among them, Ser437 was almost exclusively phosphorylated at enzyme concentrations lower than 10 μg/ml, and autophosphorylation at Ser437 was responsible for marked activation of the enzyme through decreases in the Km values for its substrates and an increase in the Vmax value. The Ca2+/calmodulin-independent activity of CaM-kinase IV was also markedly stimulated by autophosphorylation, but even after autophosphorylation it amounted only about 17% of the total enzyme activity detected in the presence of Ca2+/calmodulin.View full abstractDownload PDF (3900K) -
Hong Ma, Hong Qiong Yang, Emiko Takano, Woon Joo Lee, Masakazu Hatanak ...1993 Volume 113 Issue 5 Pages 591-599
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSCalpain requires Ca2+ for both proteolysis of its substrates and interaction with its endogenous inhibitor, calpastatin. The mechanism of inhibition of calpain by calpastatin has remained unsolved, although Nishimura and Goll [J. Biol. Chem. 266, 11842-11850 (1991)] reported that autolyzed calpain fragments containing calmodulin-like domains (CaMLDs) bound to an immobilized calpastatin column. We investigated the correlation between CaMLD-binding and calpain inhibition using immobilized columns of geneengineered CaMLDs derived from the human μ-calpain large subunit and various recombinant calpastatin mutants. Among the four internally repetitive inhibitory domains of calpastatin, each having conserved regions A, B, and C, only domains 1 and 4 showed the binding activity. The region B deletion mutant of domain 1, retaining the CaMLD-binding ability, no longer had the calpain inhibition activity, and became susceptible to proteolysis. In contrast, a synthetic oligopeptide of region B with moderate calpain inhibition activity did not bind to the column. Domain 3 acquired the binding ability on substitution of region A with that of domain 1. These results suggest that calpain inhibition and binding to the CaMLDs are not correlated or mediated by different subdomains of calpastatin.View full abstractDownload PDF (6057K) -
Ryushi Tazawa, Shinsaku Hirosawa, Ken Suzuki, Kazunori Hirokawa, Nobuo ...1993 Volume 113 Issue 5 Pages 600-606
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSThrombomodulin, a glycoprotein expressed in endothelial cells, has an important role in the blood coagulation system as a modulator. Functional characterization of the 5'-regulatory region of the human thrombomodulin gene was carried out to identify elements necessary for its expression. We used a series of dissected gene constructs containing the bacterial chloramphenicol acetyltransferase gene in transient transfection assays on human umbilical vein endothelial cells. The region extending from -290 to -33 of the 5'end flanking sequence is required for the full expression of this gene. Within this region, four potential Sp1 sites were found, and the sequences of Sp1 sites were mutated to identify their role in the promoter activity of the gene, showing that the two Sp1 sites at -207 and -141 are important for the full activity of the thrombomodulin promoter. Site-directed mutation analysis identified sequence elements GCAATC at -110 as a functioning CAAT box. Another three regions, -290 to -223, -99 to -68, and -67 to -33 have unidentified positively and negatively acting elements. A silencer element was located in the region spanning from -947 to -772 bases of the 5'end flanking region. These data indicate that the expression of the thrombomodulin gene is regulated by various elements which act positively or negatively.View full abstractDownload PDF (735K) -
Kensuke Suzuki, Yoko Furukawa, Hiro-omi Tamura, Noritaka Ejiri, Hiroyu ...1993 Volume 113 Issue 5 Pages 607-613
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSA glycosylphosphatidylinositol (GPI)-anchored protein, 5'-nucleotidase [EC 3. 1. 3. 5], was released from the membrane of bovine liver by use of phosphatidylinositol-specific phospholipase C (PI-PLC) of Bacillus thuringiensis and purified by several column chromatographies to a homogeneous state. The purified protein has an apparent molecular mass of 61 kDa, as estimated by SDS-polyacrylamide gel electrophoresis. From the partial amino acid sequence of a tryptic peptide, mixed oligonucleotides were synthesized and used to screen a λ gtll liver cDNA library, and one positive clone, pE1, was isolated. Since the insert of the clone lacked the NH2-terminal coding region, another λgt11 liver cDNA library was screened by using a synthetic probe corresponding to the 5' region of the insert of pE1. Three additional cDNA clones were obtained. Sequencing of these cDNAs revealed an open reading frame that encodes a 574-residue polypeptide with a calculated mass of 63, 084 Da. The predicted structure showed two highly hydrophobic stretches at both ends of the protein, like those of rat and human 5'-nucleotidases. The NH2-terminal 26 residues comprise a signal peptide and the COOH-terminal hydrophobic stretch may serve as a signal for the posttranslational GPI modification. An expression vector of the cDNA, pSVNT, was constructed in a mammalian expression vector pSVL and the 5'-nucleotidase activity was transiently expressed in COS-1 cells. The expressed activity was about 8 times higher than the pSVL-transfected control activity. PI-PLC released 45% of the transiently expressed 5'-nucleotidase activity, indicating that the cDNA isolated here encodes this enzyme expressed as a GPI-anchored protein.View full abstractDownload PDF (2937K) -
Jianguo Gu, Atsushi Nishikawa, Nobuo Tsuruoka, Masao Ohno, Nozomi Yama ...1993 Volume 113 Issue 5 Pages 614-619
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSA β-6N-acetylglucosaminyltransferase (GnT-V) [EC 2. 4. 1. 155] which catalyzes the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to α-D-6-mannoside has been purified up to 20, 000-fold from the cultured supernatant of the QG small lung cancer cell line with a 37% yield. The isolation procedure included chromatography on phenyl-Sepharose, hydroxylapatite, UDP-hexanolamine Sepharose, and a biantennary sugar substrate (GnGn-bi-Asn) coupled to activated CH-Sepharose 4 B. Sodium dodecyl sulfate gel electrophoresis under non-reducing conditions showed a single band of 73 kDa. Under reducing conditions, however, an additional component of 60 kDa was seen. Peptide mapping analysis indicated that both of these proteins were essentially identical, indicating that the 60-kDa component is probably a proteolytically cleaved form of the 73-kDa protein. Studies on the activity of the enzyme toward a variety of pyridylaminated sugars showed that the enzyme is most active toward triantennary (GnGnGn-tri-PA) and biantennary (GnGn-bi-PA) sugars. The Km values for GnGn-bi-PA and UDP-GlcNAc were 133 μM and 3.5mM, respectively. These studies represent the first report of the enzymatic properties of a highly purified human GnT-V.View full abstractDownload PDF (1656K) -
Shafiqul Haq, Shunji Natori, Kazuhisa Sekimizu1993 Volume 113 Issue 5 Pages 620-624
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSIn general, covalently-closed circular DNAs that are relaxed by DNA topoisomerase I at higher temperatures are more negatively (or less positively) supercoiled when analyzed at the same temperature. We found that in the presence of ethidium bromide the reaction products were less negatively supercoiled at higher temperatures. Consequently, the linking number of substrate DNA changed reversibly with temperature-shift: DNA relaxation occurred on temperature shift-up, and re-supercoiling on temperature shiftdown. Analyses of the migration of covalently closed circular DNA on agarose gel electrophoresis and of the fluorescence intensity of ethidium bromide bound to DNA indicated decrease in binding of the drug to DNA at higher temperatures. Thus, the thermal effects on the topology of the reaction products of mouse DNA topoisomerase I in the presence of ethidium bromide can be explained by the temperature-sensitive interaction of the drug with DNA.View full abstractDownload PDF (2455K) -
Francisco J. G. Muriana, Valentina Ruíz-Gutiérrez, Jos&e ...1993 Volume 113 Issue 5 Pages 625-629
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSBrush-border membrane vesicles (BBMV) were isolated from prawn hepatopancreas by a procedure involving Mg2+ preparation. The lipid composition of hepatopancreatic BBMV (hBBMV) was examined by the latroscan TLC/FID technique, and the fatty acid profile of total lipids was determined by capillary gas chromatography. hBBMV were characterized by a high content of phospholipids and cholesterol. However, the cholesterol/phospholipid molar ratio is lower in prawn than in vertebrate BBMV, which agrees well with the membrane fluidity of BBMV from different sources. The fatty acid composition of hBBMV was similar to that in marine crustacean oils. The major fatty acids present were palmitic (16:0), palmitoleic (16:1n-7), stearic (18:0), oleic (18:1n-9), and eicosapentaenoic (20:5n-3) acids. The large amount of long-chain polyunsaturated fatty acids seems to be related to a high Δ5-desaturase activity in hBBMV.View full abstractDownload PDF (624K) -
Naoki Matsumoto, Satoshi Toyoshima, Toshiaki Osawa1993 Volume 113 Issue 5 Pages 630-636
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSConcanavalin A (Con A) stimulated the phosphorylation of a protein with a molecular mass of 50 kDa and an approximate pI of 4.7 (p 50) in mouse spleen T cells. The phosphorylation of p 50 was also stimulated by a protein kinase C activator, phorbol myristate acetate (PMA), but not by a calcium ionophore, A 23187. This phosphorylation of p 50 was limited to serine and threonine residues in both Con A- and PMA-stimulated T cells. Purification and protein sequence analysis of p 50 enabled us to identify it as a lymphocyte-specific putative Ca2+-binding protein (LSP-1). These results suggest that p 50 may have some function, which is regulated through serine/threonine phosphorylation and the intracellular Ca2+ concentration, downstream of the phosphoinositide signaling system in the T cell activation cascade.View full abstractDownload PDF (2668K) -
Masakazu Oyama, Kou Kubota1993 Volume 113 Issue 5 Pages 637-641
Published: 1993
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSBacillus brevis (ATCC 8185) produces an antibiotic peptide, linear gramicidin, in the early stationary growth phase. Since we observed that preculture in milk medium is essential for production of the antibiotic in broth medium, we studied the role of the preculture in the antibiotic production. We found that addition of the supernatant of the precultured milk medium was sufficient to induce gramicidin production in broth medium. Fresh milk medium had no effect. The effector substance in the overnight cultured milk medium was labile at both acidic and alkaline pH and was destroyed by heat. We also found that addition of a protease (for example, bovine pancreas chymotrypsin or Streptomyces griseus protease) instead of the supernatant could induce the gramicidin production. Addition of Mn2+ was not required for the protease-induced production of gramicidin. It is known that B. brevis cells secrete protease into milk medium. But neither use of the protease-pretreated broth medium nor addition of casamino acids to broth medium induced gramicidin production. These results suggest that B. brevis cells secrete a factor for linear gramicidin production, that the inducing factor is protease and that the target of the protease is a substance (s) produced by the bacteria.View full abstractDownload PDF (1620K)
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