Yeast Cls2p/Csg2p localized on the endoplasmic reticulum membrane regulates a non-exchangeable intracellular Ca2+ pool cooperatively with calcineurin

AbstractSaccharromyces cerevisiae CLS2 gene product (Cls2p) that is localized on the endoplasmic reticulum is important for the regulation of intracellular Ca2+ in a compartment distinct from the vacuole. Using a vma3 mutation that impairs the Ca2+ sequestering activity into the vocuole, we have shown that the cls2 mutation results in 3.4-fold increase in the Ca2+ pool that is not exchangeable with extracellular Ca2+. Accumulation of Ca2+ within the cls2 cells is synergistically elevated by the addition of immunosuppressant, FK506. Moreover, in the vma3 background, toxicity caused by the cls2 mutation is greatly enhanced by FK506. Given that FK506 inhibits the calcineurin activity, Cls2p likely functions in releasing Ca2+ flux from the endoplasmic reticulum, somehow cooperating with calcineurin

Observation of the FeO2 and FeIVO stretching Raman bands for dioxygen reduction intermediates of cytochrome bo isolated from Escherichia coli

AbstractReaction intermediates in dioxygen reduction by the E. coli cytochrome bo-type ubiquinol oxidase were studied by time-resolved resonance Raman spectroscopy using the artificial cardiovascular system. At 0–20 μs following photolysis of the enzyme—CO adduct in the presence of O2, we observed the FeO2 stretching Raman band at 568 cm−1 which shifted to 535 cm−1 with the 18O2 derivative. These frequencies are remarkably close to those of other oxyhemoproteins including dioxygen-bound hemoglobin and aa3-type cytochrome c oxidase. In the later time range (20–40 μs), other oxygen-isotope-sensitive Raman bands were observed at 788 and 361 cm−1. Since the 781 cm−1 band exhibited a downshift by 37 cm−1 upon 18O2 substitution, we assigned it to the FeIVO stretching mode. This band is considered to arise from the ferryl intermediate, but its appearance was much earlier than the corresponding intermediate of bovine cytochrome c oxidase (> 100 μs). The 361 cm−1 band showed the 16O/18O isotopic frequency shift of 14 cm−1 similar to the case of bovine cytochrome c oxidase reaction

コウボ エキホウマク ATPase ノ コウゾウ ト キノウ

The yeast vacuolar membrane H+-ATPase (V-ATPase) is the first member of "vacuolar type" ATPase family that has been successively identified in various endocytic and exocytic membrane compartments of eukaryotic cells. The V-ATPase is a multisubunit complex composed of an integral membrane Vo sector and a peripherally associated V1 sector, the two of which are joined together with the V1-Vo bridging component. Upon ATP hydorolysis, the enzyme induces an inward current of 100 pA and generates the proton motive force of 180 mV, interior acidic and inside positive, across the vacuolar membrane. The V-ATPase family performs diverse cellular functions and maintains pH and cation homeostasis in the lumens of organelles, in the cytosol and even in the extracellular milieu. The importance of being acid in these cellular compartments has been highlighted in various cellular events such as vegetative growth, cell transformation, differentiation, metamorphosis and apoptosis

Measurement of low-energy antiproton detection efficiency in BESS below 1 GeV

An accelerator experiment was performed using a low-energy antiproton beam to measure antiproton detection efficiency of BESS, a balloon-borne spectrometer with a superconducting solenoid. Measured efficiencies showed good agreement with calculated ones derived from the BESS Monte Carlo simulation based on GEANT/GHEISHA. With detailed verification of the BESS simulation, the relative systematic error of detection efficiency derived from the BESS simulation has been determined to be $\pm$5%, compared with the previous estimation of $\pm$15% which was the dominant uncertainty for measurements of cosmic-ray antiproton flux.Comment: 13 pages, 7 figure

Precise Measurement of Cosmic-Ray Proton and Helium Spectra with the BESS Spectrometer

We report cosmic-ray proton and helium spectra in energy ranges of 1 to 120 GeV and 1 to 54 GeV/nucleon, respectively, measured by a balloon flight of the BESS spectrometer in 1998. The magnetic-rigidity of the cosmic-rays was reliably determined by highly precise measurement of the circular track in a uniform solenoidal magnetic field of 1 Tesla. Those spectra were determined within overall uncertainties of +-5 % for protons and +- 10 % for helium nuclei including statistical and systematic errors.Comment: 12 pages, 4 figure

Measurements of atmospheric muon spectra at mountain altitude

We report new measurements of the atmospheric muons at mountain altitude. The measurement was carried out with the BESS detector at the top of Mt. Norikura, Japan. The altitude is 2,770 m above sea level. Comparing our results and predictions given by some interaction models, a further appropriate model has been investigated. These studies would improve accuracy of atmospheric neutrino calculations.Comment: Mean momentum in Table 1 was correcte

Measurements of Cosmic-ray Low-energy Antiproton and Proton Spectra in a Transient Period of the Solar Field Reversal

The energy spectra of cosmic-ray low-energy antiprotons and protons have been measured by BESS in 1999 and 2000, during a period covering the solar magnetic field reversal. Based on these measurements, a sudden increase of the antiproton to proton flux ratio following the solar magnetic field reversal was observed, and it generally agrees with a drift model of the solar modulation.Comment: 4 pages, 4 figures, revised version accepted for publication in Phys. Rev. Let

Mutational analysis of the β-subunit of yeast geranylgeranyl transferase I

The gene CAL1 (also known as CDC43 ) of Saccharomyces cerevisiae encodes the β subunit of geranylgeranyl transferase I (GGTase I), which modifies several small GTPases. Biochemical analyses of the mutant-enzymes encoded by cal1 , and cdc43-2 to cdc43-7 , expressed in bacteria, have hown that all of the mutant enzymes possess reduced activity, and that none shows temerature-sensitive enzymatic activities. Nonetheless, all of the cal1/cdc43 mutants show temperature-sensitive growth phenotypes. Increase in soluble pools of the small GTPases was observed in the yeast mutant cells at the restrictive temperature in vivo, suggesting that the yeast prenylation pathway itself is temperative sensitive. The cal-1 mutation, located most proximal to the C-terminus of the protein, differs from the other cdc43 mutations in several respects. An increase in soluble Rholp was observed in the cal-1 strain grown at the restrictive temperature. The temperature-sensitive phenotype of cal-1 is most efficiently suppressed by overproduction of Rholp. Overproduction of the other essential target, Cdc42p, in contrast, is deleterious in cal-1 cells, but not in other cdc43 mutants or the wild-type strains. The cdc43-5 mutant cells accumulate Cdc42p in soluble pools and cdc43-5 is suppressed by overproduction of Cdc42p. Thus, several phenotypic differences are observed among the cal1/cdc43 mutations, possibly due to alterations in substrate specificity caused by the mutations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42258/1/438-252-1-2-1_62520001.pd

Identification of proline carrier in Escherichia coli K-12

AbstractProline carrier, a product of the put P gene of Escherichia coli, was identified as a 35 kDa cytoplasmic membrane protein by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Its identification was based on the following evidence: First, the density of the band corresponding to a 35 kDa protein correlated with the proline-binding activity of cytoplasmic membranes from put P-deficient and put P-amplified strains. Second, by the differential labeling method, the 35 kDa protein was specifically labeled with radioactive N-ethyl-maleimide. The 35 kDa protein was found to aggregate on heat treatment and to show abnormal mobility on SDS-PAGE