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S Hatano

Publications and source records attributed to S Hatano.

At least 19 recordsLinked to original sources
PubMed1992

Identification of actin kinase activity in purified fragmin-actin complex.

Actin kinase phosphorylates actin of fragmin-actin complex, resulting in the inactivation of the nucleation and capping activities of the complex. Fragmin-actin complex was prepared by a new purification procedure. Incubation with ATP caused inactivation of the purified complex and phosphorylation of actin of fragmin-actin complex. The detailed analysis of the complex by SDS-gel electrophoresis showed that actin kinase was co-purified with the fragmin-actin complex. Formation of such an association between actin kinase and substrate suggests that the kinase is localized on the fragmin-actin complex to efficiently regulate actin cytoskeletons.

Actins↗
PubMed1992

Requirement of phosphatidylinositol 4,5-bisphosphate for alpha-actinin function.

Inositol phospholipid turnover is enhanced during mitogenic stimulation of cells by growth factors and the breakdown of phosphatidylinositol 4,5-bisphosphate (PtdInsP2) may be important in triggering cell proliferation. PtdInsP2 also binds actin-binding proteins to regulate their activity, but it is not yet understood how this control is achieved. The protein alpha-actinin from striated muscle contains large amounts of endogenous PtdInsP2, whereas that from smooth muscle has only a little but will bind exogenously added PtdInsP2. In vitro alpha-actinin binds to F-actin and will crosslink actin filaments, increasing the viscosity of F-actin solutions. We report here that alpha-actinin from striated muscle is an endogenous PtdInsP2-bound protein and that the specific interaction between alpha-actinin and PtdInsP2 regulates the F-actin-gelating activity of alpha-actinin. Although the F-actin-gelating activity of alpha-actinin from smooth muscle is much reduced compared with that from striated muscle, exogenous PtdInsP2 can enhance the activity of smooth muscle alpha-actinin to the level seen in striated muscles. These results show that PtdInsP2 is present in striated muscle alpha-actinin and that it is necessary for alpha-actinin to realize its maximum gelating activity.

Actinin↗
PubMed1992

Inositol phospholipid-induced suppression of F-actin-gelating activity of smooth muscle filamin.

Filamin, a high molecular weight actin-binding protein, cross-links actin filaments and produces a gel composed of F-actin. The effects of polyphosphoinositides on the gelating activity of smooth muscle filamin were examined by measuring the low shear viscosity of the F-actin solutions containing filamin incubated with phosphatidylinositol (PI), phosphatidylinositol 4-monophosphate (PIP), or phosphatidylinositol 4,5-bisphosphate (PIP2). Micelles of these inositol phospholipids bound to filamin inhibited the ability to form a gel of F-actin. The inhibiting activity of each phospholipid was in the following order, PIP2 greater than PIP greater than PI. The F-actin binding assay of filamin revealed that the inhibition of F-actin-gelation resulted in the loss of the F-actin-binding activity of filamin. Thus, polyphosphoinositides may play important roles in regulating the gelating activity of filamin.

Actins↗
PubMed1992

Phosphorylation by actin kinase of the pointed end domain on the actin molecule.

Fragmin from plasmodium of Physarum polycephalum binds G-actin and severs F-actin in the presence of Ca2+ over 10(-6) M. The fragmin-actin complex consisting of fragmin and G-actin nucleates actin polymerization and caps the barbed (fast growing) end of F-actin, regardless of the concentrations of Ca2+, and the actin filaments are shortened. Actin kinase purified from plasmodium abolishes the nucleation and capping activities of the complex by phosphorylating actin of the fragmin-actin complex (Furuhashi, K., and Hatano, S. (1990) J. Cell. Biol. 111, 1081-1087). This inactivation of the complex leads to production of long actin filaments. We obtained evidence that Physarum actin is phosphorylated by actin kinase at Thr-201, and probably at Thr-202 and/or Thr-203, with 1 mol of phosphate distributed among them. This finding raises the possibility that the site of phosphorylation, Thr-201 to Thr-203, is positioned on the pointed (slow growing) end domain of the actin molecule, because growth of actin filaments from the fragmin-actin complex occurs only from the pointed end. These observations are consistent with a model of the three-dimensional structure of G-actin. Inactivation of the fragmen-actin complex may follow phosphorylation of the pointed end domain of actin.

Actins↗
PubMed1992

Actin kinase: a protein kinase that phosphorylates actin of fragmin-actin complex.

Actin of fragmin-actin complex is phosphorylated by an endogenous kinase from plasmodium of Physarum polycephalum. The phosphorylation abolishes the nucleation and capping activities of fragmin-actin complex. The kinase has been purified and termed actin kinase [Furuhashi, K. & Hatano, S. (1990) J. Cell Biol. 111, 1081-1087]. Enzymatic properties of the purified actin kinase were studied in detail. Actin kinase exhibited the highest activity under conditions physiological for the plasmodium (30 mM KCl, 6 mM MgCl2, pH 7.0). The Vmax and the Km of the enzyme for ATP were about 83 mumol/min/mg and 25 microM, respectively. The Km for fragmin-actin complex was 190 nM. The purified actin kinase phosphorylated actin of fragmin-actin complex at a constant rate regardless of Ca2+ concentration. Similarly, 2 microM cAMP, 2 microM cGMP, 2 micrograms/ml calmodulin in the presence of Ca2+ or 1 mM GTP showed no effect on the activity of the purified enzyme. Actin kinase did not phosphorylate histone H1, H2B, alpha-casein, or beta-casein, suggesting that actin kinase is a new kind of protein kinase which specifically phosphorylates actin of the fragmin-actin complex.

Actins↗
PubMed1979

Some properties of Physarum actinin. A regulatory protein of actin polymerization.

A factor termed Physarum actinin was isolated and partially purified from plasmodia of a myxomycete, Physarum polycephalum. When Physarum actinin was mixed with purified Physarum or rabbit striated muscle G-actin in a weight ratio of about 1 actinin to 9 actin and then the polymerization of G-actin induced, G-actin polymerized to the ordinary F-actin on addition of 0.1 M KCl. However, it polymerized to Mg-polymer on addition of 2 mM MgCl2. The reduced viscosity (etasp/C) of the Mg-polymer was 1.2 dl/g, about one-seventh of that of the F-actin (7.4 dl/g). The sedimentation coefficient of the Mg-polymer was 22.8 S, almost the same as that of the F-actin (29.4 S). The Mg-polymer showed the specific ATPase activity of the order of 1 . 10(-3) mumol ATP/mg actin per min. It was shown that Physarum actinin copolymerized with G-actin to form Mg-polymer on addition of 2 mM MgCl2. The molecular weights of Physarum actinin were about 90 000 in salt-free or slat solutions and 43 000 in a dodecyl sulfate solution. The range of salting out with ammonium sulfate was 50--65% saturation, which was different from that of Physarum actin (15--35% saturation). Physarum actinin did not interact with Physarum myosin or muscle heavy meromyosin. When the weight ratio of actinin to actin increased, the flow birefringence of the formed Mg-polymer decreased, and it became almost zero at the weight ratio of 1 actinin to 5 actin. ATPase activity reached the maximum level (2.2 . 10(-3) mumol ATP/mg actin per min) at the same ratio. On the addition of Physarum actinin to purified Physarum F-actin which had been polymerized on addition of 2 mM MgCl2 the viscosity decreased rapidly, suggesting that the F-actin filaments were broken in the smaller fragments or that they transformed to Mg-polymers. A factor with properties similar to Physarum actinin was isolated from acetone powder of sea urchin eggs.

Actinin↗
PubMed1979

Relationship of relevant factors of atherosclerosis to menopause in Japanese women.

The relationship of menopause to associated factors of atherosclerosis was investigated during October 1973 to December 1976. The subjects were 1674 premenopausal and 428 postmenopausal women aged 35 to 54, who were living in Toda city, an urban area of Japan. Serum cholesterol and triglyceride were higher in postmenopausal women than in premenopausal women. This trend was also observed in serum uric acid and blood hemoglobin. On the other hand, systolic and diastolic blood pressure and relative body weight had no consistent relationship to menopause.

Adult↗
PubMed1979

Crystallization and preliminary crystallographic data of chicken gizzard G-actin . DNase I complex and Physarum G-actin . DNase I complex.

Smooth muscle G-actin from chicken gizzard and Physarum plasmodium G-actin both interact with DNase I and form 1 : 1 complexes. These complexes were crystallized by using polyethylene glycol 6000 as a precipitant. Both crystals belong to the same orthorhombic space group P2(1)2(1)2(1). The cell dimensions of chicken gizzard G-actin.DNase I complex are a=42.00 +/- 0.07 A, b=225.3 +/- 0.4 A, and c=77.4 +/- 0.1 A, while those of Physarum G-actin.DNase I complex are a=42 A, b=221 A, and c=77 A.

Actins↗
PubMed1978

Reversible superprecipitation and bundle formation of plasmodium actomyosin.

Synthetic actomyosin from plasmodium was found to undergo reversible superprecipitation upon addition of ATP. According to electronmicroscopic investigation upon clearing, short myosin filaments of about 0.2 micron in length appeared predominantly coexisting with actin filaments, and after superprecipitation, bundles of actin filaments were formed where short myosin filaments or myosin molecules were bound to the side of the bundle, making a whisk-like structure. The turbidity and the ATPase activity of actomyosin were measured at various ATP concentrations clamped by using an ATP-regenerating system. The turbidity was high below 1 . 10(-6) M ATP, corresponding to the state of superprecipitation, and with increasing ATP concentration it dropped in the range of 1 . 10(-6)--1 . 10(-5) M ATP. On the other hand, the ATPase activity was low below 1 . 10(-6) M ATP and increased above 1 . 10(-5) M after the turbidity dropped. Characteristic features of superprecipitation of plasmodium actomyosin observed here were discussed in relation to the mechanism of motility in vivo.

Actins↗
PubMed1978

Ketamine-diazepam anaesthesia for abdominal surgery. A review of 1000 cases with continuous "Micro-Mini" drip administration technique.

During a twenty-one month period, over 1000 patients who underwent various types of intra-abdominal operations were anaesthetized with a combination of diazepam and ketamine using a continuous "Micro-Mini" drip administration technique. The results obtained from 1000 cases were eminently satisfactory. This paper also reviews all the previous literature on ketamine anaesthesia related to abdominal surgery. All the undesirable adverse side effects associated with ketamine anaesthesia in adult patients have been almost completely eliminated using this technique. Overall, the excellent results clearly indicate that ketamine has a definite place in anaesthesia for intra-abdominal operations.

Abdomen↗