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Biomedical subjects

S Ebashi

Publications and source records attributed to S Ebashi.

At least 19 recordsLinked to original sources
PubMed1994

Is phosphorylation the main physiological action of myosin light chain kinase?

The 155-kDa component of bovine stomach, which exhibits a strong actomyosin (AM) activating activity and a relatively weak myosin light chain kinase (MLCK) activity, has a strong affinity for the actin filament and the actin-binding site is confined to an 80 amino acid residue on its N-terminal side. This affinity may play a crucial role in AM activation. Some reagents preferentially abolish either the AM-activating effect or MLCK activity. In conclusion, MLCK of the 155-kDa component does not play a fundamental role in activating the AM system as far as the in vitro system is concerned. The possible mechanism of AM activation by the component is discussed.

Actomyosin↗
PubMed1994

Subgingival plaque formation on single and polycrystal aluminum ceramics.

A study was conducted to investigate subgingival plaque formation on two types of dental implant material in the human oral cavity. Fifteen teeth affected by severe periodontitis and scheduled for extraction in five patients were selected. After thorough root planing, inlay cavities were prepared from the gingival margin to 5 mm subgingivally. Then, rectangular test specimens (polycrystal aluminum ceramic (P), single-crystal aluminum ceramic (S)) or a control dentin specimen (D) were installed in gold inlays, which were placed in the inlay cavities and left for 3, 7 or 21 d. As a consequence, 4 mm of the surface of each specimen was exposed to the environment of the periodontal pocket. After each test period, the specimens were removed from the inlays and examined by scanning electron microscopy (SEM). The results suggested that S is a more suitable dental implant material than P from the viewpoint of clinical application because of its lower degree of plaque accumulation.

Adult↗
PubMed1993

Complexes of myosin subfragment 1 with pyrophosphate and with adenosine diphosphate as studied by phosphorus-31 nuclear magnetic resonance.

Myosin subfragment-1.pyrophosphate (S1.PPi) complex and S1.ADP complex were observed with 31P NMR at various temperatures between 0 and 25 degrees C. The signal of S1.PPi complex showed a small temperature dependence, indicating that a single conformation exists for the complex. It also showed that the electron density around phosphorus nuclei was increased upon the formation of complex. On the other hand, the signal of S1.ADP complex was clearly dependent on temperature and indicated the presence of two forms, i.e., high-temperature and low-temperature forms. In the high-temperature form, the electron density around beta-phosphate was decreased upon the formation of complex with S1. In the low-temperature form, the distribution of electrons around phosphorus nuclei is extremely anisotropic due to the tight interaction of S1 and the phosphate moieties of ADP.

Adenosine Diphosphate↗
PubMed1992

Isolation of cDNA for bovine stomach 155 kDa protein exhibiting myosin light chain kinase activity.

Two proteins with myosin light chain kinase activity and electrophoretic molecular weights of 155,000 and 130,000 were each isolated from bovine stomach smooth muscle [Kuwayama, H., Suzuki, M., Koga, R., & Ebashi, S. (1988) J. Biochem. 104, 862-866]. The 155 kDa component showed a much higher superprecipitation-inducing activity than the 130 kDa component, when compared on the basis of equivalent myosin light chain kinase activity. In this study, we isolated a cDNA for the entire coding region of the 155 kDa protein. The deduced amino acid sequence revealed a high degree of similarity to those of chicken and rabbit smooth muscle myosin light chain kinases. Multiple motifs, such as three repeats of an immunoglobulin C2-like domain, a fibronectin type III domain, and unusual 20 repeats of 12 amino acids were detected in the sequence. Part of the amino-terminal sequence was similar to that of the actin- and calmodulin-binding domain of smooth muscle caldesmon. These observations suggest that the 155 kDa protein has additional functions other than its enzymatic activity. Two mRNAs of 6.0 and 2.6 kb in length in the bovine stomach smooth muscle RNAs were hybridized with cDNA probes. The 2.6-kb RNA probably encodes telokin, which is the carboxyl terminus of smooth muscle myosin light chain kinase. mRNAs with identical lengths were also detected in bovine aorta.

Amino Acid Sequence↗
PubMed1991

[Inorganic ions versus proteins in biological functions].

Physiological studies on inorganic ions were historically reviewed. Extremely asymmetric distribution of Ca2+ inside and outside the cell is the basis of its unparalleled role in intracellular processes. This must be rightly appreciated from the viewpoint of the origin of life, where the attention has exclusively been focused on the protein so far. Recognition of the importance of Ca2+ and other inorganic ions as the essential factor in these meanings may be a key for elucidating the strategy of the life.

Adenosine Triphosphatases↗
PubMed1990

Sea urchin protease specific to the SPKK motif in histone.

A protease activity specific to spermatogenous histones was found in the egg extract of sea urchin. The enzyme responsible for this activity, named SPKK protease because of its substrate specificity, was purified as a monomeric 28 kDa protein. SPKK protease activity is inhibited by leupeptin and is specific to the repeat of sequences like Ser-Pro-Lys-Lys (the SPKK motif) [Suzuki, M. (1989), EMBO J. 8, 797-804]. The DNA-binding sites of sea urchin spermatogenous histones H1 and H2B, which protect the linker DNA of chromatin, are made up of sequences rich in the SPKK motif. SPKK protease may contribute not only to the unpacking of sperm chromatin but also to transcription activation of the male origin gene at fertilisation. SPKK protease resembles another protease activity on nucleolin [Burger et al. (1982) Eur. J. Biochem. 128 475-480] in its characteristics.

Amino Acid Sequence↗
PubMed1990

Histone H1 kinase specific to the SPKK motif.

A protein kinase phosphorylating sea urchin spermatogenous histones, H1 and H2B, was found in sea urchin egg homogenate and purified. The kinase is activated by cAMP and is composed of two different types of subunits with molecular masses 41 and 46 kDa. The kinase phosphorylates a peptide, Ser-Pro-Arg-Lys-Ser-Pro-Arg-Lys, which is a double repeat of the DNA-binding SPKK motif [Suzuki M., (1989) EMBO J. 8, 797-804]. We name this kinase SPkinase because it exclusively phosphorylates H1 and H2B, the only histones containing SPKK motifs. Phosphorylation of H1 by SPkinase decreases the DNA-binding ability of H1. This paper is the first to report purification of a kinase which affects the DNA-binding ability of a gene regulatory protein.

Amino Acid Sequence↗
PubMed1988

Ca2+ in contractile processes.

The concept of Ca2+ regulation, first discovered and developed in muscle research, is historically surveyed. Ca2+ regulation mechanisms in actomyosin-dependent contractile processes are compared, emphasis being placed on the great diversity. The mode of action of Ca2+ is discussed with the examples of troponin and calmodulin, the most differentiated and conservative Ca2+-receptor proteins, respectively.

Actomyosin↗
PubMed1988

Preparation of tubulin from Caulerpa, a marine green alga, using casein as a protective agent against proteolytic degradation.

Bidirectional organelle movements taking place in the cytoplasm of the rhizomes of Caulerpa, a coenocytic marine green alga, have been indicated to be dependent on microtubules (Kuroda, K. & Manabe, E. (1983) Proc. Jpn. Acad. 59B, 131-134; Manabe, E. & Kuroda, K. (1984) Proc. Jpn. Acad. 60B, 118-121). However, when a crude extract of Caulerpa rhizomes was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and subjected to immunoblotting with monoclonal anti-tubulin antibody, no reacting band could be detected. This apparent absence of tubulin in the extract was found to be a result of the complete degradation of tubulin by potent intrinsic proteolytic activity. All of the commercially available protease inhibitors so far tested (p-chloromercuriphenylsulfonic acid, phenyl methylsulfonyl fluoride, 1-chloro-4-phenyl-3-tosylamido-2-butanone, 7-amino-1-chloro-3-tosylamido-2-heptanone, p-tosyl-L-arginine methyl ester, soybean trypsin inhibitor, antipain, chymostatin, leupeptin, and pepstatin) failed to inhibit the activity completely. But addition of casein at the concentration of 1% (weight per volume) to the solutions used for preparation was effective in protecting tubulin from proteolytic degradation, thus making it possible to prepare tubulin from the crude extract of Caulerpa. On SDS-PAGE, the Caulerpa alpha-tubulin thus prepared was a little smaller in molecular weight than that of rabbit brain.

Animals↗
PubMed1988

Isolation from bovine brain of 155 kDa component exhibiting myosin light chain kinase activity.

1) Taking myosin light chain kinase (MLCK) activity as the index, bovine extract was fractionated by the use of anion-exchange chromatography, cation-exchange chromatography, and calmodulin affinity chromatography. The kinase activity of the fraction thus obtained was elevated up to about 12,400 times over that of the original crude extract. 2) The fraction mentioned above was subjected again to anion exchange chromatography. The kinase activities were divided into two parts, i.e., part I which contained the 155 kDa component and part II which was virtually free of 155 kDa component. The MLCK activity of part I was considerably lower than that of part II. 3) Part I was subjected to gel filtration using AcA 34 gel and the 155 kDa component was isolated. The fraction contained the 155 kDa component in a homogeneous state and showed myosin specific kinase activity, which was about 2 X 10(5) times that of the original crude extract. 4) The high kinase activity of part II seemed to be ascribable to the 130 kDa component, in accord with the report of Hathaway, Adelstein, and Klee (J. Biol. Chem. 256, 8183-8189, 1981).

Amino Acids↗
PubMed1988

Preparation of protein components exhibiting myosin light chain kinase activities from bovine aorta: discrepancies between its enzyme activity and actomyosin activating effect.

1) Two protein components, 155 and 130 kDa in their electrophoretic molecular weights, respectively, were isolated in a homogeneous state from bovine aorta; they showed both the superprecipitation-inducing effect on desensitized natural actomyosin and the myosin light chain kinase (MLCK) action on gizzard myosin. 2) The superprecipitating activity of the 155 kDa component was 5 time higher than that of the 130 kDa component on the basis of equivalent MLCK activity. 3) The same procedure was applied to bovine stomach, giving rise to a 155 kDa component in a homogeneous state as in the case of aorta, but the 130 kDa component thus prepared was contaminated by higher molecular weight components. 4) If compared on the basis of equivalent MLCK activity, bovine stomach 155 kDa component showed more than 10 times higher superprecipitating activity than the fraction that contained the 130 kDa component as the main constituent. 5) The discrepancy between the superprecipitating activity and MLCK activity mentioned above was discussed in relation to the Ca2+ regulation mechanism in smooth muscle contraction. The possibility that the 130 kDa component might be a proteolytic product of the 155 kDa component was also discussed.

Actomyosin↗