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排序方式: 共有1119条查询结果,搜索用时 15 毫秒
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M Ohtsubo M Yoshida S Ohta Y Kagawa M Yohda T Date 《Biochemical and biophysical research communications》1987,146(2):705-710
Using site-directed mutagenesis, Glu-190 or Glu-201 of the beta subunit of the F1-ATPase from the thermophilic bacterium PS3 were replaced with glutamine. It was possible to reconstitute complexes of the mutated beta subunits with alpha and gamma subunits, but the complexes did not have ATPase activity. It is concluded that carboxylic acid side chains of Glu-190 and Glu-201 of the beta subunit are essential for catalytic activity of F1-ATPase. 相似文献
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K Denda J Konishi T Oshima T Date M Yoshida 《The Journal of biological chemistry》1988,263(13):6012-6015
Isolation of novel membrane-associated ATPases, presumably soluble parts of the H+-ATPases, from archaebacteria has been recently reported, and their properties were found to be significantly different from the usual F1-ATPase. In order to assess the relationship of the archaebacterial ATPases to the F1-ATPases and other known ATPases, the amino acid sequence of the alpha subunit of the ATPase from Sulfolobus acidocaldarius, an acidothermophilic archaebacterium, was compared with the sequences of other ATPases. The gene encoding its alpha subunit was cloned from the genomic library of S. acidocaldarius, and the nucleotide sequence was determined. The 591-amino acid sequence deduced from the nucleotide sequence contains a small number of short stretches that shows sequence similarity to the alpha and beta subunits of F1-ATPase. However, the overall similarity is too weak to consider it to be a typical member of the F1-ATPase family when the highly conserved sequences of the F1-ATPase subunits among various organisms are taken into account. Moreover, most of these stretches overlap the consensus sequences that are commonly found in some nucleotide-binding proteins. There is no significant sequence similarity to the ion-translocating ATPases, which form phosphorylated intermediates, such as animal Na+,K+-ATPases. Thus, the S. acidocaldarius ATPase and probably other archaebacterial ATPases also appear to belong to a new group of ion-translocating ATPases that has only a distant relationship to F1-ATPase. 相似文献
6.
Tomizawa Ken-ichi; Ito Naoko; Komeda Yoshibumi; Uyeda Taro Q. P.; Takio Koji; Furuya Masaki 《Plant & cell physiology》1991,32(1):95-102
The pea phytochrome I (PI) cDNA clone, pPP1001, was expressedin E. coli. The plasmid pPP1001 contains pea PI cDNA which coversthe entire coding region with the Shine-Dalgarno consensus sequencejoined upstream of the cDNA in an expression vector pNUT6. ThepPP1001 transformants formed typical inclusion bodies when culturedat 32?C. However, when cultured at 37?C or in the presence ofisopropyl-ß-D-thiogalactopyranoside (IPTG) at 32?C,the bacteria lysed before inclusion body formation. Immuno-stainingwith anti-PI monoclonal antibody, mAP5, of transformants fixedby cold methanol showed that stainable materials were distributedin whole cytoplasmic region. When the inclusion bodies wereobserved clearly, the regions corresponding to the inclusionbodies became difficult to stain. Western blot analysis, however,showed that a ca. 100 kDa PI polypeptide was detected in thefraction from inclusion bodies and a ca. 90 kDa PI polypeptidefrom the soluble fraction. The amino acid sequence analysisof purified 100 kDa PI sample indicated that its amino terminusis blocked. However, minor signals in one experiment yieldeda sequence corresponding to the expected amino terminus of peaPI except for the initiation methionine. One of the anti-peaPI monoclonal antibodies, mAP9, that recognizes the near N-terminusof pea phytochrome was reactive to the 100 kDa polypeptide. (Received June 22, 1990; Accepted November 18, 1990) 相似文献
7.
Summary Changes in the intracellular distribution of microtubules and microfilaments during amoeba-to-flagellate and flagellate-to-amoeba transformations inPhysarum polycephalum were examined by fluorescence microscopy using anti-tubulin antibody and NBD-phallacidin, respectively. Amoebae contained an extensive microtubular cytoskeleton, which was converted to a flagellar cone structure during transformation to flagellates in liquid medium. When flagellates reverted back to amoebae, this conical structure disintegrated prior to flagella resorption. Amoebae showed some microfilament-enriched domains along the periphery, from which numerous filamentous extrusions, probably pseudopods and filopods, emanated. Flagellates contained a ridge, a sheet-like structure, along their dorsal axis, especially in the earlier stages of flagellation. Another microfilament-enriched thick filamentous structure ran along the dorsal axis, starting from the anterior tip of the cell. This structure apparently coincided spatially with one of the bundles of microtubules. During the reversion to amoebae, other localized microfilaments were transiently observed at the posterior end. A model of cytoskeletal changes in the transformations between these two cell types was proposed. 相似文献
8.
12-O-Tetradecanoylphorbol-13-acetate (TPA) is a well-known tumor promoter in mouse-skin carcinogenesis. Its effects on mutagenesis in a soybean test system were examined, and the effects were judged from the appearance of spots of various colors on the leaves. When soybean seeds were treated with TPA plus 0.03% caffeine, the frequency of spots per leaf decreased significantly and in proportion to the concentration of TPA. TPA alone at concentrations of 1–20 μg/ml did not induce any mutations. Mutations induced by γ-rays were not affected by administration of TPA either before or after exposure to γ-rays. The mechanism of suppression by TPA of mutations induced by caffeine is discussed. 相似文献
9.
Homogeneous populations of hybrid alpha 3 beta 3 gamma complexes of the thermostable F1-ATPase containing one, two, or three copies of the mutationally impaired beta subunits were produced using the solid phase reconstitution method. Two kinds of mutated beta subunits were used for the reconstitution, one of which lacked the ability to bind any adenine nucleotides. The complexes containing one impaired beta and two wild-type beta subunits retained a significant amount of ATPase activity with cooperative kinetics, whereas those containing two or three impaired beta subunits showed very little ATPase activity. These results imply that the catalysis of steady-state ATP hydrolysis can proceed even if one of the three beta subunits in F1-ATPase is not functional. 相似文献
10.
Taro Q. P. Uyeda 《Journal of plant research》1996,109(3):231-239
Recent breakthroughs and technological improvements are rapidly generating evidence supporting the “swinging lever arm model”
for force production by myosin. Unlike previous models, this model posits that the globular domain of the myosin motor binds
to actin with a constant orientation during force generation. Movement of the neck domain of the motor is hypothesized to
occur relative to the globular domain much like a lever arm. This intramolecular conformational change drives the movement
of the bound actin. The swinging lever arm model is supported by or consistent with a large number of experimental data obtained
with skeletal muscle or slime mold myosins, all of which move actin filaments at rates between 1 and 10 μm/sin vitro. Recently myosin was purified, fromChara internodal cells.In vitro the purifiedChara myosin moves actin filaments at rates one order of magnitude faster than the “fast” skeletal muscle myosin. While this ultra
fast movement is not necessarily inconsistent with the swinging lever arm model, one or more specific facets of the motor
must be altered in theChara motor in order to accommodate such rapid movement. These characteristics are experimentally testable, thus the ultra fast
movement byChara myosin represents a powerful and compelling test of the swinging lever arm model. 相似文献