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Y Tonomura

Publications and source records attributed to Y Tonomura.

At least 19 recordsLinked to original sources
PubMed2006

Coexistence of Ramsay Hunt syndrome and varicella-zoster virus encephalitis.

We describe a patient with Ramsay Hunt syndrome and varicella-zoster virus encephalitis. The coexistence of these conditions is rare and to our knowledge has not been clearly documented in the English-language literature. We summarize the clinical characteristics of our patient and seven similar patients described in previous reports, including those published in Japanese. Although concomitant diseases such as diabetes and chronic renal failure may lead to an aggressive course, all patients described in detail have had good outcomes.

Acyclovir↗
PubMed1994

[The clinico-pathological significance of hematuria in diabetics].

A clinico-pathological study was performed on 154 patients with diabetes mellitus to clarify the significance of glomerular hematuria. Glomerular hematuria was observed in 26 patients (16.9%), of whom 10 had complications of IgA glomerulonephritis and one had membranous nephropathy. The remaining patients (143 cases) were divided into two groups; a hematuria group (15 cases) and a non-hematuria group (128 cases). Patients in the hematuria group showed diabetic retinopathy, hypertension, massive proteinuria and the requirement for insulin therapy more often than those in the non-hematuria group (p < 0.01, p < 0.001, p < 0.001 and p < 0.01, respectively). In addition, the serum creatinine level in the hematuria group was significantly elevated compared to that in the non-hematuria group (p < 0.01). Histologically, patients in the hematuria group exhibited advanced diffuse lesions, nodular lesions, exudative lesions, microaneurysms, crescent formation, capsular adhesion and interstitial lesions more often than those in the non-hematuria group (all, p < 0.001). Furthermore, the vascular index in the hematuria group was significantly higher than that in the non-hematuria group (p < 0.001). It is suggested that glomerular hematuria in diabetic patients indicates the presence of diabetic nephropathy at an advanced stage or coexistence of primary glomerulonephritis.

Adolescent↗
PubMed1984

Comparative study of the kinetic and structural properties of monomeric and oligomeric forms of sarcoplasmic reticulum ATPase.

Sarcoplasmic reticulum (SR) isolated from rabbit muscle was treated with N-ethyl-maleimide (NEM) to specifically inhibit the dephosphorylation step of the Ca2+,Mg2+-dependent ATPase reaction. However, when this membrane was solubilized with dodecyl octaethyleneglycol monoether (C12E8), rapid decomposition of the phosphoenzyme (EP) was observed both in the absence and presence of Mg2+. When the detergent was removed from the reaction mixture, the inhibition of EP decomposition by NEM was observed again. These results support our previous suggestion (1,2) that in the presence of high concentrations of C12E8, EP may be hydrolyzed to produce P1 in a manner different from the reaction in the native SR ATPase. Gel filtration of the solubilized ATPase was performed in the presence of low concentrations of C12E8 to elute ATPase aggregates of various sizes. Two distinct fractions were selected after column chromatography and their physical and kinetic properties were compared. The molecular weights of the ATPase proteins of these two fractions were determined to be about 150 and 360K daltons with Stokes radii of about 5.5 and 8.0 nm, respectively. The Stokes radii agreed with the values obtained from polarization decay measurement data of N-1-pyrene maleimide (N-1-P)-labeled ATPase aggregates separated on the same column. The rate of EP decomposition was determined for the two column fractions described above. After the addition of EDTA the EP decomposition rate of the smaller-sized ATPase was much higher than the EP decomposition rate of the larger-sized ATPase.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Requirement of phosphorylation of Physarum myosin heavy chain for thick filament formation, actin activation of Mg2+-ATPase activity, and Ca2+-inhibitory superprecipitation.

In an attempt to elucidate the Ca2+-regulated mechanism of motility in Physarum plasmodia, we improved the preparation method for myosin B and pure myosin. The obtained results are as follows: 1. We obtained two types of myosin B which are distinguishable from each other with respect to their sensitivity to Ca2+. The inactive type of myosin B had low superprecipitation activities both in the presence and in the absence of Ca2+. The active type showed very high superprecipitation activity in EGTA, and the activity was conspicuously inhibited by Ca2+. The active type was converted into the inactive type by treatment with potato acid phosphatase. Also the inactive type or the phosphatase-treated active type was converted into the active type upon reacting with ATP-gamma-S. 2. In the reaction with ATP-gamma-S, only the myosin HC of myosin B was phosphorylated. The phosphorylation was independent of Ca2+ and calmodulin, and the extent was about 1 mol/mol HC. 3. The Ca2+ sensitivity in the superprecipitation of the active type was not decreased by adding an excess amount of F-actin. Besides, the actin-activated Mg2+-ATPase activity of purified phosphorylated myosin was not Ca2+-sensitive. Therefore, presence of a Ca2+-dependent inhibitory factor(s) that could bind to myosin was suggested. 4. The Mg2+-ATPase activity of purified phosphorylated myosin was 7-8 times enhanced by F-actin, but that of dephosphorylated myosin was hardly activated at all. 5. In a gel filtration in 0.5 M KCl, phosphorylated myosin was eluted behind dephosphorylated myosin. Electron microscopy applying the rotary-shadow method showed significant difference in flexibility in the tail between phosphorylated and dephosphorylated myosin molecules. 6. In 40 mM KCl and 5-10 mM MgCl2, phosphorylated myosin formed thick filaments, but dephosphorylated myosin did not, whether there was ATP or not. The above results clearly show that the phosphorylation of myosin HC is indispensable to ATP-induced superprecipitation, the actin-activated Mg2+-ATPase activity, and the formation of thick filaments of myosin. A myosin-linked factor(s) that inhibits an actin-myosin interaction in a Ca2+-dependent manner may exist.

Actins↗
PubMed1983

Morphological aspects of thiophosphorylated and dephosphorylated myosin molecules from the plasmodium of Physarum polycephalum.

Electron microscopically, the myosin molecule from the plasmodium of Physarum polycephalum has a long tail of 173 nm, having a flexible region over the range of 80 to 120 nm from the head-tail junction. In 0.6 M ammonium acetate, this region of the dephosphorylated myosin molecules is more flexible than that of the thiophosphorylated ones. In 50 mM ammonium acetate, the dephosphorylated myosin molecules exist in monomeric and oligomeric forms, independently of ATP and Mg2+, whereas the thiophosphorylated myosin molecules form dense aggregates of thick filaments. The tails of the monomeric dephosphorylated myosin molecules bend sharply at the flexible region at angles of more than 120 degrees. In oligomers of the dephosphorylated myosin molecules, the molecules are all associated side-to-side with straight tails and are oriented in the same direction. Based on these results, the regulation mechanism of cell motility of the plasmodium is discussed.

Fungal Proteins↗
PubMed1983

The gating behavior of a channel for Ca2+-induced Ca2+ release in fragmented sarcoplasmic reticulum.

Fragmented sarcoplasmic reticulum (FSR) from rabbit skeletal muscle was passively loaded with 45Ca2+. Its Ca2+-induced Ca2+ release was measured in the presence of 0.1 M KCl and 5 mM MgCl2 at 0 degrees C by Millipore filtration. The following results were obtained. 1. The amounts of Ca2+-induced Ca2+ release from heavy SR, light SR, and unfractionated SR were 80, 20, and 60% of the amounts of preloaded Ca2+, respectively. Therefore, the experiments were carried out with unfractionated FSR. 2. The Ca2+-induced Ca2+ release from FSR was inhibited by procaine, but unaffected by caffeine and trifluoperazine. The rate of Ca2+ release decreased markedly with decreasing pH. 3. Various adenine nucleotides (ATP, AMPPNP, ADP, AMP) accelerated the Ca2+ release, and the accelerating effect was reversible. CTP had no effect on the release, but inhibited the accelerating effect of AMPPNP. 4. In the presence of 15 microM external free Ca2+, the final amount of the Ca2+ release was unaffected. The rate of Ca2+ release was markedly increased by AMP; the dependence of the rate on AMP concentration followed a Michaelis-Menten type equation with a Hill coefficient of 1 and an apparent affinity for AMP of about 2 mM. 5. In the presence of AMP, the amount of Ca2+ released increased, while the relative rate was unaffected by increasing the external Ca2+ concentration. The final amount released increased from 0 to 60% of the amount of preloaded Ca2+ by increasing the free Ca2+ concentration from 0.06 to 0.24 microM. The effect of external Ca2+ on the release was reversible. 6. The ratio between the amount of preloaded Ca2+ and that of Ca2+ release was independent of the Ca2+ concentration used for preloading. Furthermore, the dependence of the final amount of Ca2+-induced Ca2+ release on external Ca2+ was unaffected by internal Ca2+.

Animals↗
PubMed1983

Reaction mechanism of 21S dynein ATPase from sea urchin sperm. II. Formation of reaction intermediates.

The amounts of ATP and ADP bound to 21S dynein during the ATPase reaction were measured in the presence of 2.83 mg/ml 21S dynein, 2 mM PEP, 4 mg/ml PK, 0.1 M KCl, 5 mM MgCl2, 1 mM DTT, 0.1 mM PMSF, 50% [2-3H]glycerol, and 20 mM imidazole at pH 7.0 and 0 degrees C. The maximum amounts of ATP and ADP bound to 21S dynein were 0.29 and 0.55 mol/(10(6) g protein), respectively. The dissociation constants of ATP for the ATP and ADP binding (4 microM) were almost equal to the Km value (3.7 microM) of dynein-ATPase in the steady state. The amount of bound ADP during the initial phase showed an overshoot, which reached 0.6-0.8 mol/10(6) g protein at 5 s, then decreased to the steady state level within 20 s. Furthermore, the rate of TCA-Pi liberation during the initial 5 s was 6 times the steady-state rate. The apparent Pi-burst size, estimated by extrapolating the steady-state Pi liberation to zero time, was 1.33 mol/(10(6) g protein). The true Pi-burst size was calculated to be 1.56 mol/(10(6) g protein) by correcting for the effect of Pi liberation at steady state. All these findings could be explained quantitatively by the following reaction scheme for 21S dynein ATPase in the presence of glycerol: (formula; see text) where K1 = 25.5 microM, and k2, k3, and k4 were 0.39, 0.21, and 0.11 s-1, respectively.

Adenosine Diphosphate↗
PubMed1983

Energy transfer between fluorescent dyes attached to Ca2+,Mg2+-ATPase in the sarcoplasmic reticulum.

Sarcoplasmic reticulum (SR) isolated from rabbit skeletal muscle was solubilized with a nonionic detergent, dodecyl octaethyleneglycol monoether (C12E8), at a weight ratio of detergent to protein of greater than 10, so that the Ca2+, Mg2+ dependent ATPase existed mainly in a monomeric form (7). The solubilized ATPase was reacted with 10 microM N-1-P or 5 microM DACM in the presence of 5 mM CaCl2, 0.4 M KCl, 20% glycerol and 50 mM TES at pH 7.5 and 20 degrees C. Under these conditions, about 1 mol of N-1-P was incorporated into 10(5) g SR protein on 10 min incubation and 1 mol of DACM was incorporated into the same amount of SR on 5 min incubation. Analysis of the tryptic digest of the N-1-P- or DACM-labeled. ATPase on SDS polyacrylamide gel revealed that almost all the fluorescence was associated with the 30K m.w. subfragment of the ATPase protein. Even when the amount of the probe incorporated into SR-ATPase was increased from 1 to 3 mol per 10(5) g SR protein, all was incorporated into the 30K subfragment. Both the activities of formation and decomposition of the phosphorylated intermediate (EP) were unaffected by these modifications. When the separately labeled ATPases were mixed together in the presence of C12E8 and the detergent was removed by incubation with Bio-Beads SM-2, a significant amount of fluorescence energy transfer was observed between N-1-P and DACM. However, energy transfer did not occur when the labeled ATPases were mixed after removal of C12E8.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

The binding of ATP to the catalytic and the regulatory site of Ca2+, Mg2+-dependent ATPase of the sarcoplasmic reticulum.

Two kinds of ATP binding sites were found on the ATPase molecule in deoxycholic acid-treated sarcoplasmic reticulum. One was the catalytic site (1 mol/mol active site) and its affinity was high. Upon addition of Ca2+, all the ATP bound to the catalytic site disappeared at 75 mM KCl, while a significant amount of ATP remained bound to the site at 0-2 mM KCl. The latter binding was found to be due to the formation of a slowly exchanging enzyme--ATP complex, which is in equilibrium with phosphoenzyme + ADP. The other binding site was the regulatory one (1 mol/mol active site) and its affinity was low, changing only insignificantly upon addition of Ca2+. The ATP binding to the regulatory site shifted the equilibrium between the slowly exchanging complex and EP toward EP.

Adenosine Triphosphate↗
PubMed1982

A novel 36,000-dalton actin-binding protein purified from microfilaments in Physarum plasmodia which aggregates actin filaments and blocks actin-myosin interaction.

In the plasmodia of Physarum polycephalum, which show a cyclic contraction-relaxation rhythm of the gel layer, huge aggregates of entangled actin microfilaments are formed at about the onset of the relaxation (R. Nagai, Y. Yoshimoto, and N. Kamiya. 1978. J. Cell Sci. 33:205-225). By treating the plasmodia with Triton X-100, we prepared a demembranated cytoskeleton consisting of entangled actin filaments and found that the actin filaments hardly interact with rabbit skeletal myosin. From the cytoskeleton we purified a novel actin-binding protein which binds stoichiometrically to actin and makes actin filaments curled and aggregated. It also inhibits the ATPase activity as well as the superprecipitation of reconstituted rabbit skeletal muscle actomyosin. This protein has a polypeptide molecular weight of 36,000 and binds 7 mol of actin/mol 36,000 polypeptide.

Actins↗
PubMed1982

Changes in affinity for calcium ions with the formation of two kinds of phosphoenzyme in the Ca2+,Mg2+-dependent ATPase of sarcoplasmic reticulum.

The amount of Ca2+ bound to the Ca2+,Mg2+-dependent ATPase of deoxycholic acid-treated sarcoplasmic reticulum was measured during ATP hydrolysis by the double-membrane filtration method [Yamaguchi, M. & Tonomura, Y. (1979), J. Biochem. 86, 509--523]. The maximal amount of phosphorylated intermediate (EP) was adopted as the amount of active site of the ATPase. In the absence of ATP, 2 mol of Ca2+ bound cooperatively to 1 mol of active site with high affinity and were removed rapidly by addition of EGTA. AMPPNP did not affect the Ca2+ binding to the ATPase in the presence of MgCl2. Under the conditions where most EP and ADP sensitive at steady state (58 microM Ca2+, 50 microM EGTA, and 20 mM MgCl2 at pH 7.0 and 0 degrees C), bound Ca2+ increased by 0.6--0.7 mol per mol active site upon addition of ATP. The time course of decrease in the amount of bound 45Ca2+ on addition of unlabeled Ca2+ + EGTA was biphasic, and 70% of bound 45Ca2+ was slowly displaced with a rate constant similar to that of EP decomposition. Similar results were obtained for the enzyme treated with N-ethylmaleimide, which inhibits the step of conversion of ADP-sensitive EP to the ADP-insensitive one. Under the conditions where most EP was ADP insensitive at steady state (58 microM Ca2+, 30 microM EGTA, and 20 mM MgCl2 at pH 8.8 and 0 degrees C), the amount of bound Ca2+ increased slightly, then decreased slowly by 1 mol per mol of EP formed after addition of ATP. Under the conditions where about a half of EP was ADP sensitive (58 microM Ca2+, 25 microM EGTA, and 1 mM MgCl2 at pH 8.8 and 0 degrees C), the amount of bound Ca2+ did not change upon addition of ATP. These findings suggest that the Ca2+ bound to the enzyme becomes unremovable by EGTA upon formation of ADP-sensitive EP and is released upon its conversion to ADP-insensitive EP.

Adenosine Diphosphate↗
PubMed1982

Desensitization to Mg2+ of the phosphoenzyme in sarcoplasmic reticulum Ca2+-ATPase by the addition of a nonionic detergent and the restoration of sensitivity after its removal.

Sarcoplasmic reticulum (SR) membranes from rabbit skeletal muscle were solubilized with a high concentration of dodecyl octaethyleneglycol monoether (C12E8) and the kinetic properties of the Ca2+,Mg2+-dependent ATPase [EC 3.6.1.3] were studied. The following results were obtained: 1. SR ATPase solubilized in C12E8 retains high ability to form phosphoenzyme ([EP] = 4--5 mol/10(6) g protein) for at least two days in the presence of 5 mM Ca2+, 0.5 M KCl, and 20% glycerol at pH 7.55. 2. The ATPase activity was dependent on both Mg2+ and Ca2+. However, the rate of E32P decay after the addition of unlabeled ATP was independent of Mg2+. 3. Most of the EP formed in the absence of Mg2+ was capable of reacting with ADP to form ATP in the backward reaction. However, in the presence of 5 mM Mg2+, the amount of ATP formed was markedly reduced without loss of the reactivity of the EP with ADP. 4. The removal of C12E8 from the ATPase by the use of Bio-Beads resulted in the full restoration of the Mg2+ dependency of the EP decomposition. 5. These results strongly suggest that in the case of SR solubilized with a high concentration of C12E8 the decomposition of phosphoenzyme is Mg2+ independent and ATP is mainly hydrolyzed through Mg2+-dependent decomposition of an enzyme-ATP complex, which is in equilibrium with phosphoenzyme and ADP.

Adenosine Diphosphate↗
PubMed1982

Regulation of binding of myosin subfragments with regulated actin by calcium ions in the presence of magnesium ATP.

Previously, several workers reported that at very low ionic strength and in the presence of ATP, the extent of binding of S-1 with the F-actin-tropomyosin-troponin complex or regulated actin (FA-TM-TN) is unaffected by removal of Ca2+. However, in this study we found that during the ATPase reaction at physiological ionic strength, the extent of binding of HMM with FA-TM-TN decreased markedly upon removal of CA2+. Therefore, the effects of Ca2+ were studied on the intermediate steps in the acto-HMM or acto-S-1 ATPase reaction. 1. The nucleotide-induced dissociation of acto-s-1 was studied using AMPPNP as substrate. The extent of binding of S-1 with regulated actin in the presence of Mg2+-AMPPNP increased in a sigmoidal manner as the S-1 concentration increased. When the molar ratio of actin monomer to S-1 was higher than 5-10, the removal of Ca2+ shifted the equilibrium of the dissociation reaction, FA-S-1-AMPPNP in equilibrium FA + S-1-AMPPNP, to the right. 2. The recombination rate of HMMPADP or S-1PADP with regulated actin in the absence of free Mg2+-ATP was estimated by measuring the time course of recovery in light-scattering intensity after addition of ATP. The rate decreased upon removal of Ca2+, when the molar ratio of actin monomer to S-1 was higher than 5-10. 3. The decomposition rate of HMMPADP was measured in the presence of Mg2+-ATP. In the absence of Ca2+, regulated actin did not affect this rate, whereas in its presence, regulated actin markedly accelerated the rate. These findings clearly indicated that at physiological ionic strength, removal of Ca2+ affects various elementary steps in the ATPase reaction to promote the dissociation of myosin heads from FA-TM-TN.

Actins↗
PubMed1982

Nonlinear dependence of actin-activated Mg2+-ATPase activity on the extent of phosphorylation of gizzard myosin and H-meromyosin.

1. The actin-activated Mg2+-ATPase activity of gizzard HMM increased in proportion to the square of the extent of LC phosphorylation. This result indicates that the LCs of HMM are randomly phosphorylated, and the phosphorylation of both heads of HMM is required for the activation of HMM Mg2+-ATPase by F-actin. 2. In 75 mM KCl, the Mg2+-ATPase activity of gizzard myosin was activated by F-actin only slightly when a half of the total LC was phosphorylated. From 1 to 2 mol LC phosphorylation, the activity was enhanced by F-actin almost linearly. In 30 mM KCl, the activity of acto-gizzard myosin increased sigmoidally with increase in the extent of LC phosphorylation. On electron microscopy, side-by-side aggregates of myosin filaments were observed in 30 mM KCl, but not in 75 mM KCl. It was suggested that the activation of the Mg2+-ATPase activity of acto-gizzard myosin LC phosphorylation is modified by formation of myosin filaments and their aggregates. 3. The relationship between the actin-activated Mg2+-ATPase activity of HMM or myosin and the extent of LC phosphorylation was unaffected by tropomyosin.

Actins↗
PubMed1982

Differences in chemical structure around the reactive lysine residues in the burst and the nonburst heads of skeletal muscle myosin.

Our laboratory has presented strong evidence for the nonidentical two-headed structure of skeletal muscle myosin. We previously showed that each of the two kinds of heads, i.e., the burst head, which forms the myosin-P-ADP complex, and the nonburst head, which forms the myosin-ATP complex upon reaction with ATP, contains 1 mol of reactive lysine residue per mol which is modified rapidly with TNBS. We also found that in the presence of PPi only the reactive lysine residue in the burst head is modified with TNBS. Utilizing this phenomenon, we presented evidence [(1981) J. Biochem. 89, 831-839] indicating that the chemical structures around the reactive lysine residues in the burst and the nonburst head are different. In this study, we determined the amino acid sequence around the reactive lysine residues to demonstrate the nonidentical chemical structure of the two heads of skeletal muscle myosin. We found that the sequence around the reactive lysine residue in the burst head was ....Pro-Met-Asn-Pro-Pro-Lys-Tyr.... and the sequence in the nonburst head was ....Ser-Met-Asn-Pro-Pro-Lys-Tyr..... Thus, a proline residue located ner the reactive lysine residue in the burst head was found to be replaced by a serine residue in the nonburst head.

Adenosine Diphosphate↗