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1.
T Kanazawa 《The Journal of biological chemistry》1975,250(1):113-119
A large fraction of the Ca-2plus- and Mg-2plus-dependent ATPase (EC 3.6.1.3) in sarcoplasmic reticulum membranes solubilized with Triton X-100 was phosphorylated with Pi. The phosphorylation required Mg-2plus but was strongly inhibited by low concentrations of Ca-2plus. A Ca-2plus ion concentration of 30 muM caused half-maximum inhibition in the presence of 50 mM MgCl2. The phosphorylated enzyme showed a rapid turnover and was in dynamic equilibrium with Pi in the medium. At equilibrium the amount of the phosphorylated enzyme increased markedly with increased in the reaction temperature. The apparent standard free energy change, the apparent standard enthalpy change, and the apparent standard entropy change in the formation of the phosphorylated enzyme from the enzyme-phosphate complex in the presence of excess Mg-2plus at 37 degrees and pH 7.0 were, respectively, 0.35 Cal per mol, 15.9 Cal per mol, and 50.2 e.u. per mol. The susceptibility of the acid-denatured phosphorylated enzyme to hydroxylamine showed that the phosphorylated enzyme is of an acyl phosphate type. The present results are consistent with the probability that the phosphorylation results from reversal of late steps in the Ca-2plus transport process. The results clearly show that the phosphorylated enzyme is stabilized by a great increase in entropy upon its formation from the enzyme-phosphate complex. 相似文献
2.
H Suzuki M Obara H Kuwayama T Kanazawa 《The Journal of biological chemistry》1987,262(32):15448-15456
Sarcoplasmic reticulum vesicles were modified with a fluorescent thiol reagent, N-iodoacetyl-N'-(5-sulfo-1-naphthyl)ethylenediamine. One mol of readily reactive thiols per mol of the Ca2+-ATPase was labeled without a loss of the catalytic activity. The fluorescence of the label increased by 8% upon binding of Ca2+ to the high affinity sites of the enzyme. This fluorescence enhancement probably reflects a conformational change responsible for Ca2+-induced enzyme activation. Upon addition of ATP to the Ca2+-activated enzyme, the fluorescence decreased by 15%. This fluorescence drop and formation of the phosphoenzyme intermediate were determined under the same conditions with a stopped-flow apparatus and a rapid quenching system. The amplitude of the fluorescence drop thus determined was saturated with 3 microM ATP. This shows that the fluorescence drop was caused by ATP binding to the catalytic site. In contrast, the rate of the fluorescence drop was not saturated even with 50 microM ATP. The fluorescence drop coincided with phosphoenzyme formation at 0.5 or 3 microM ATP, but it became much faster than phosphoenzyme formation when the ATP concentration was raised to 100 microM. These results indicate that the ATP-induced fluorescence drop reflects a conformational change in the enzyme.ATP complex. The fluorescence drop was accompanied by a red spectrum shift, which suggests that the label was exposed to a more hydrophilic environment. The electrophoretic analysis of the tryptic digest of the labeled enzyme (10.9 kDa) showed that almost all of the label was located on the 5.2-kDa fragment which includes the carboxyl terminus and the putative ATP-binding domain. The sequencing of the two major labeled peptides, which were isolated from the thermolytic digest of the labeled enzyme, revealed that the labeled site in either of these peptides was Cys674. It seems likely that the label bound to this Cys674 could be involved in the observed fluorescence changes. 相似文献
3.
Insulin induces chloroquine-sensitive recycling of insulin-like growth factor II receptors but not of glucose transporters in rat adipocytes 总被引:1,自引:0,他引:1
Incubation of insulin-treated rat adipocytes with chloroquine, in a time- and concentration-dependent manner, was observed to inhibit the insulin-stimulated increase in insulin-like growth factor II (IGF-II) binding activity, whereas no significant change in IGF-II binding was observed in the absence of insulin. The incremental increase of insulin-stimulated IGF-II binding was inhibited 50% by 0.2 mM chloroquine within 15 min and was nearly completely abolished by 60 min. Interestingly, IGF-II binding was never observed to decrease below the binding value in cells without insulin treatment even when incubation was extended to 180 min. Scatchard analysis of IGF-II binding as well as the specific binding of an anti-IGF-II receptor antibody demonstrated that the loss of IGF-II binding in the insulin-stimulated chloroquine-treated adipocytes was due to a decrease in the number of cell-surface IGF-II receptors, whereas the total number of cellular IGF-II receptors was unaltered. The effect of chloroquine was observed to be reversible, temperature-dependent, and sensitive to the metabolic poison KCN. Furthermore, NH4Cl was also observed to inhibit insulin-stimulated increase in IGF-II binding. In contrast, chloroquine or NH4Cl did not inhibit the basal or insulin-stimulated glucose transport activity. Photoaffinity labeling of the glucose transporter with [3H]cytochalasin B also demonstrated that the basal and insulin-stimulated subcellular distribution of the glucose transporters was unaltered by chloroquine treatment. These results suggest that 1) insulin induces a constitutive, acidotropic agent-sensitive recycling of IGF-II receptor and 2) the glucose transporter and IGF-II receptor do not share the same insulin-regulated intracellular trafficking pathways. 相似文献
4.
Transfer of granulomatous inflammation with nonviable preparations of schistosome granulomas in naive mice 总被引:1,自引:0,他引:1
Hepatic granulomas of euthymic (nu/+) mice infected with Schistosoma mansoni were freeze-dried or freeze-thawed 3 times and transplanted subcutaneously into naive nu/+ and athymic (nu/nu) mice. The grafted sites, studied histologically, showed formation of organized granulomas in nu/+ mice similar to donor granulomas as observed after grafting of freshly isolated granulomas. On the other hand, in nu/nu mice, the nonviable transplants elicited small and disorganized granulomas, like hepatic granulomas in nu/nu mice with schistosomiasis, but different from fresh nu/+ transplants in nu/nu skin. The findings indicate viable cells are not required for transfer of granulomatous reactions, but T cells are needed for full expression. 相似文献
5.
Atsuko Matsuoka Akiko Hirosawa Shinasku Natori Shigeo Iwasaki Toshio Sofuni Motoi Ishidate Jr. 《Mutation research》1989,215(2):179-185
The chromosomal aberration test using a Chinese hamster lung cell line (CHL) was carried out on ptaquiloside and its related compounds, hypoloside B, hypoloside C, illudin M and illudin S. Ptaquiloside induced chromosomal aberrations at doses as low as 4.5 μg/ml (0.0113 mM). The clastogenic effect was ph-dependent. The same activity was observed at a 90-fold higher dose at pH 5.3 in the culture medium compared with the activity at pH 74. or pH 8.0. Both hypoloside B and hypoloside C were also clastogenic at almost the same dose levels as that of ptaquiloside. Illudin M and illudin S were also potet clastogens and induced aberrations at much lower doses than ptaquiloside. These results suggest that the clastogenic effect is involved in the mechanism of carcinogenic potency of ptaquiloside in animals. 相似文献
6.
Endothelin-3 is a novel neuropeptide: isolation and sequence determination of endothelin-1 and endothelin-3 in porcine brain 总被引:4,自引:0,他引:4
O Shinmi S Kimura T Sawamura Y Sugita T Yoshizawa Y Uchiyama M Yanagisawa K Goto T Masaki I Kanazawa 《Biochemical and biophysical research communications》1989,164(1):587-593
The molecular forms of endothelin (ET) related peptides were investigated in porcine brain by using high performance liquid chromatography coupled with three specific radioimmunoassays. ET-1 and its oxidized form were isolated and sequenced as in the case of porcine spinal cord. A very small amount of big ET-1 (1-39) and its C-terminal fragment (big ET-1 (22-39] were also detected. Furthermore, immunoreactive (ir)-ET-3 was isolated and sequenced; its partial primary structure was identical to that of human (rat) ET-3. The concentrations of ir-ET-1 and ir-ET-3 in porcine brain were 140 fmol/g tissue and 5 fmol/g tissue, respectively. These results indicate that besides ET-1, ET-3 is a novel neuropeptide in the central nervous system. 相似文献
7.
Presence of endothelin-1 in porcine spinal cord: isolation and sequence determination 总被引:2,自引:0,他引:2
O Shinmi S Kimura T Yoshizawa T Sawamura Y Uchiyama Y Sugita I Kanazawa M Yanagisawa K Goto T Masaki 《Biochemical and biophysical research communications》1989,162(1):340-346
We investigated the molecular forms of endothelin (ET) related peptides in porcine spinal cord by high performance liquid chromatography coupled with radioimmunoassays using three antisera raised against ET-1 and C-terminal fragments of ET-1 and big ET-1. ET-1 and its oxidized form were isolated as major immunoreactive peptides and sequenced. Furthermore, immunoreactivities like ET-3 and big ET-1(22-39) (contents: less than 8% and less than 1% of ET-1, respectively) were detected based on their chromatographic retention times and characteristics of immunoreactivity to the antisera. Big ET-1 was only scarcely detected. Immunohistochemical study showed the presence of ET-1-like immunoreactivity in motoneurons, dorsal horn neurons and dot- and fiber-like structures in the dorsal horn of lumbar spinal cord. These results indicate that ET-1 is present not only in endothelial cells but also in spinal cord, and that big ET-1 is converted into ET-1 in spinal cord by specific processing between Trp21-Val22. The data also indicate that ET-1 may act as a neuropeptide in the central nervous system. 相似文献
8.
Studies on DNA markers (D4S10 and D4S43/S127) genetically linked to Huntington's disease in Japanese families 总被引:1,自引:0,他引:1
Ichiro Kanazawa Ikuko Kondo Joh-E Ikeda Teruaki Ikeda Yuichior Shizu Mitsuo Yoshida Hirotaro Narabayashi Shigetoshi Kuroda Hisayuki Tsunoda Eiji Mizuta Yoko Okuno Kiyotaka Sugawara Miho Murata Mafuyu Takahashi James F. Gusella 《Human genetics》1990,85(3):257-260
Summary This is the first full report on the genetic linkage between Japanese Huntington's disease and the DNA markers D4S10 and D4S43/S127. With use of the HindIII, BglI, and EcoRI polymorphisms detected at D4S10, and the combination of all these polymorphisms to give composite haplotypes, nine Japanese Huntington's disease families were found to be informative. Three recombinants for D4S10 were detected in these families, giving a maximum lod score of 1.662 at a of 0.10. Similarly, when we used the MspI and PvuII polymorphisms detected by D4S43/S127, five families gave informative results. No recombinant was detected in these families, giving a maximum lod score of 3.348 at a of 0.00. These results clearly support the view that the Japanese Huntington's disease gene may be identical with the Western gene, in spite of the lower prevalence rate in Japan. 相似文献
9.
10.
Atsuko Yamagata 《Molecular reproduction and development》1988,19(2):215-225
The ultrastructural features of spermatogenesis were investigated in the hermaphroditic sea star Asterina minor. The primordial germ cells in the genital rachis contain small clusters of electron-dense material (nuage material) and a stack of annulate lamellae. They also have a flagellum and basal body complex situated close to the Golgi complex. After the development of the genital rachis into the ovotestis, spermatogenic cells increase in number and differentiation begins. Nuage material is observed in spermatogonia, but it gradually disappears in spermatocytes. The annulate lamellae do not exist beyond the early spermatogonial stage. By contrast, a flagellum and basal body complex are found throughout spermatogenesis. The Golgi-derived proacrosomal vesicles appear in the spermatocyte and coalesce to form an acrosomal vesicle in the early spermatid. The process of acrosome formation is as follows: (1) a lamella of endoplasmic reticulum (ER) continuous with the outer nuclear membrane encloses the posterior portion of the acrosomal vesicle; (2) the vesicle attaches to the cell membrane with its anterior portion; (3) periacrosomal material accumulates in the space between the acrosomal vesicle and the ER; (4) the nucleus proper changes its features to surround the acrosome; (5) amorphous, electron-dense material is deposited under the electron-dense disk; and (6) the nucleus forms a hollow opposite the electron-dense material. 相似文献