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Volume 10 (1985)
- Issue 4 Pages 315-
- Issue 3 Pages 195-
- Issue 2 Pages 95-
- Issue 1 Pages 1-
Volume 10, Issue 2
Displaying 1-10 of 10 articles from this issue
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Hirao Kohno, Shigeru Taketani, Rikio Tokunaga1985 Volume 10 Issue 2 Pages 95-104
Published: 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSWhen human erythroleukemia cells (K562) were exposed to phorbol-12-myristate 13-acetate (PMA), phosphorylation of transferrin receptors was enhanced 5-fold with 10-7 M PMA and 7-fold with 10-6M PMA, but not with 4α-phorbol (5 × 10-7 M). Stimulation took place in serine residues in the cytoplasmic domain of the receptor. Although phosphorylation in the control cells took place in both cell-surface and intracellular receptors, phosphorylation in PMA-treated cells increased only in the cell-surface receptors, not in the intracellular receptors. The number of receptors on the cell surface increased slightly with the increase in phosphorylation at the cell surface, in the PMA-treated cells. No difference in transferrin binding was found for the control and PMA-treated cells. These results indicate that enhanced phosphorylation of the transferrin receptor takes place on the cell surface only and that it presumably is mediated by protein kinase C.View full abstractDownload PDF (6237K) -
Kazuhiro Nagata, Kuniaki Takagi, Takashi Hashida, Yasuo Ichikawa1985 Volume 10 Issue 2 Pages 105-120
Published: 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSCell extracts of a murine leukemia cell line, Ml, apparently contain three kinds of actin-gelation factors; a filamin-like protein, and 38Kdimer and 105K-dimer proteins. Unlike gelation by the filamin-like protein, gelation by the latter two proteins is inhibited by low concentrations of KCl. Our study of the 38K protein has been reported elsewhere (Takagi, K. et al., J. Biochem. Tokyo 97, 605-616, 1985). We here describe the purification and characterization of the 105K protein.
The 105K protein differs from the a-actinin group of proteins in its antigenicity, peptide components and Ca2+-insensitivity. The saturated binding ratio of the protein to purified skeletal muscle actin is 1 : 8; when this ratio exceeds 1 : 20, gelation takes place. This gelation is inhibited completely by the presence of 25 mM KC1. Electron microscopy revealed that, in the absence of KC1, the 105K protein/actin mixture forms short actin bundles that are accompanied by a meshwork of short single filaments. The presence of 25 mM KC1 did not prevent actin-bundling, but the bundles became longer and the meshwork of short filaments was no longer present.View full abstractDownload PDF (12082K) -
Sachiko Kajigaya, Kazuo Kubota, Nagahiro Minato, Tetsuo Sudo, Kiyohiko ...1985 Volume 10 Issue 2 Pages 121-131
Published: 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSAn interleukin-2 (IL-2)-independent murine lymphocyte clone (2E10.4.13) with the Thyl+Lyt1+2-T200+ phenotype was separated from theoriginal IL-2-dependent natural killer (NK) cell line (PEC-1). Erythroid burst-promoting activity (BPA), erythropoietin (Ep), granulocyte/macrophage, megakaryocyte and eosinophil colony-stimulating factors (GM-, MK-and Eo-CSF), IL-2 and Interleukin-3 (IL-3) were produced when these cells were stimulated with phorbol myristate acetate (PMA). When the conditioned medium was run through ion-exchange high-performance liquid chromatography, BPA, Ep, GM-CSF, MK-CSF and Eo-CSF were eluted in the same region as IL-3. In contrast, MK-CSF, much of the GM-CSF and half of the Eo-CSF were eluted in a distinct region where no IL-3 was detected. Chemical analyses of the hemopoietic factors derived from a single T inducer clone indicated that all the hemopoietic activities were associated with IL-3 activity. Some CSF activities (GM-, MK-and Eo-CSF) also could be mediated by the distinct molecules from IL-3, evidence that heterogeneous molecules are responsible for CSF activity.View full abstractDownload PDF (1098K) -
Soichi Nakamura, Noburo Kamiya1985 Volume 10 Issue 2 Pages 133-141
Published: 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSShort-term changes in the cytoplasmic pH in the plasmodium of Physarum polycephalum were measured with special reference to its con-traction-relaxation cycle. The measurement was done photometrically in a plasmodial strand segment loaded with fluorescein diacetate. To eliminate possible errors caused by volume changes of the plasmodial strand in the course of its contraction-relaxation cycle, fluorescence intensities at two excitation wavelengths, 493 nm (pH sensitive) and 448 nm (pH insensitive), were recorded alternately. Simultaneously, tension production of the same strand segment was recorded under isometric conditions. The results were : 1) The cytoplasmic pH averaged 6.6 ± 0.5, for 34 specimens. 2) The cytoplasmic pH changed cyclically with the same period as the tensile force. 3) The average peak-to-peak amplitude of pH change was 0.13 ± 0.06 pH unit. 4) The phase of the pH oscillation was just opposite to that of the force production cycle; i.e., the cytoplasmic pH decreased during the contraction phase and increased during the relaxation phase.View full abstractDownload PDF (777K) -
Soichi Nakamura, Noburo Kamiya1985 Volume 10 Issue 2 Pages 143-149
Published: 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSCyclic changes in the pH of the slime layer on the surface of the Physarum plasmodium (surface pH) were measured, with special reference to the contraction-relaxation cycle. Measurements were made with a specially designed small antimony electrode. The oscillation detected was confirmed by spectrophotometry with a pH indicator dye (bromcresol purple). A clear cor-relation was found between cyclic changes in the surface pH of a plasmodial strand segment and the contraction-relaxation cycle. The surface pH oscillated with the same period but in opposite phase to the cyclic tensile force pro-duction, as does the cytoplasmic pH. The peak-to-peak amplitude of the oscillation usually was of the order of a 0.1 pH unit or less. No stretch acti-vation was found with the pH oscillation.View full abstractDownload PDF (636K) -
Shunji Kasai, Hirofumi Arimura, Masayuki Nishida, Tadakazu Suyama1985 Volume 10 Issue 2 Pages 151-159
Published: 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe relative fibrin-binding, fibrinolytic and fibrinogenolytic properties of single-chain pro-urokinase, an inactive proenzyme form of human urokinase purified from cultured human kidney cells, and urokinase were compared. The affinity of single-chain pro-urokinase for fibrin was much higher than that of urokinase. In Vitro thrombolytic studies showed that single-chain pro-urokinase is approximately three times more potent in fibrinolysis than urokinase and that it does not degrade fibrinogen in the plasma at a concentration, at which complete plasma clot lysis takes place; whereas, urokinase extensively degrades the fibrinogen in the plasma.
These specific, potent thrombolytic properties of single-chain pro-urokinase seem to be due to its high affinity for fibrin and to its conversion from the inactive single-chain form to the active two-chain form on the thrombus by the catalytic amount of plasmin generated during coagulation. This singlechain pro-urokinase obtained from human kidney cells by tissue culture should prove advantageous than urokinase in thrombolytic therapy.View full abstractDownload PDF (980K) -
Takemi Enomoto, Masashi Suzuki, Mikiko Takahashi, Katsumif Kawasaki, Y ...1985 Volume 10 Issue 2 Pages 161-171
Published: 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSTwo forms of DNA polymerase α, αl and α2, have been partially purified from mouse FM3A cells by discriminating one form from the other on the basis of the association of primase activity. The primase activity in the most purified α1 fraction co-sedimented with the DNA polymerase activity in a glycerol gradient, and almost no primase activity was detected in the most purified α2 fraction. The primase activity associated with DNA polymerase α was assayed indirectly by measuring ATP-dependent DNA synthesis with poly (dT) as template. Characterization of the assay system was performed with the purified α1. The system was absolutely dependent on the presence of ATP and a divalent cation. Mn2+ was much more effective than Mg2+, and 5-fold higher activity was observed with Mn2+ than with Mg2+ at their optimal concentrations. The primase activity assayed by the above system showed sensitivity to (NH4)2SO4 very similar to that of free primase reported by Tseng and Ahlem (J. Biol. Chem. 258, 9845-9849, 1983). The activity was inhibited by more than 50 % by 20 mM (NH4)2SO4.
α1 and α2 were very similar as DNA polymerases in their sensitivity to several inhibitors and their preference for template-primers, except that al had a slightly greater preference for poly (dT)•(rA)10 than α2 did. The major difference between the two forms was observed in their S values, 8.2 and 6.4 S for α1 and α2, respectively.View full abstractDownload PDF (1132K) -
Soichi Nakamura, Noburo Kamiya1985 Volume 10 Issue 2 Pages 173-176
Published: 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe surface pH of a Physarum plasmodium advancing on an agar plate with a definite antero-posterior polarity was measured with a small antimony pH combination electrode. There was a clear pH gradient over the plasmodium surface from the advancing front (pH 6.6 ± 0.1) to the rear (pH 5.6 ± 0.4), whereas the surface pH of freshly formed endoplasmic drops was 6.9 ± 0.3. In addition to this regional pH difference, an oscillation of pH was detected over the entire plasmodium surface. In the front zone this oscillation did not disappear even when a small area surrounding the electrode tip was disconnected from the rest of the plasmodium, but in the strand region the oscillation disappeared as soon as the strand was disconnected near the electrode tip from the rest of the plasmodium. It took 10-20 min before the oscillation began again in the disconnected strand. This shows that the active site of oscillation is only in the front region and that the rest of the plasmodium is somehow under the control of the front part.View full abstractDownload PDF (345K) -
Kozo Utsumi, Koichi Nobori, Masanobu Miyahara1985 Volume 10 Issue 2 Pages 177-181
Published: 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe putative ionophoretic action of phosphatidic acid or arachidonic acid metabolites for Ca2+ has offered an attractive explanation for stimulation-coupled mobilization of cytoplasmic Ca2+. We have examined the effects of Ca2+ ionophore and long-chain unsaturated fatty acids on the translocation of Ca2+ across the liposomal membrane by using Quin II-entrap-ped liposomes, a sensitive assay system for ionophoresis of Ca2+. A23187 increased Quin II fluorescence intensity corresponding to the translocation of Ca2+ into liposomes. Similar translocation was observed with unsaturated long-chain fatty acids but not with saturated fatty acids. Thus, when phospholipases of cell membrane are activated by certain stimuli, unsaturated long-chain fatty acids are liberated and might mediate the mobilization of cytoplasmic Ca2+.View full abstractDownload PDF (495K) -
H. Stanley Bennett1985 Volume 10 Issue 2 Pages 183-193
Published: 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDownload PDF (1321K)
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