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81.
Toshinobu Tokumoto Masakane Yamashita Mika Tokumoto Yoshinao Katsu Ryo Horiguchi Hiroko Kajiura Yoshitaka Nagahama 《The Journal of cell biology》1997,138(6):1313-1322
Immediately before the transition from metaphase to anaphase, the protein kinase activity of maturation or M-phase promoting factor (MPF) is inactivated by a mechanism that involves the degradation of its regulatory subunit, cyclin B. The availability of biologically active goldfish cyclin B produced in Escherichia coli and purified goldfish proteasomes (a nonlysosomal large protease) has allowed the role of proteasomes in the regulation of cyclin degradation to be examined for the first time. The 26S, but not the 20S proteasome, digested recombinant 49-kD cyclin B at lysine 57 (K57), producing a 42-kD truncated form. The 42-kD cyclin was also produced by the digestion of native cyclin B forming a complex with cdc2, a catalytic subunit of MPF, and a fragment transiently appeared during cyclin degradation when eggs were released from metaphase II arrest by egg activation. Mutant cyclin at K57 was resistant to both digestion by the 26S proteasome and degradation at metaphase/anaphase transition in Xenopus egg extracts. The results of this study indicate that the destruction of cyclin B is initiated by the ATP-dependent and ubiquitin-independent proteolytic activity of 26S proteasome through the first cutting in the NH2 terminus of cyclin (at K57 in the case of goldfish cyclin B). We also surmise that this cut allows the cyclin to be ubiquitinated for further destruction by ubiquitin-dependent activity of the 26S proteasome that leads to MPF inactivation. 相似文献
82.
Teruo Yamashita Kenji Sakae Shinichi Kobayashi Yuichi Ishihara Takashi Miyake Agboatwalla Mubina Shin Isomura 《Microbiology and immunology》1995,39(6):433-435
Aichi virus was isolated in Vero cells from 5 (2.3%) of 222 Pakistani children with gastroenteritis but none was found in 91 healthy children. Aichi virus was also isolated from 5 (0.7%) of 722 Japanese travelers returned from tours to Southeast Asian countries and complained of gastrointestinal symptoms at the quarantine station of Nagoya International Airport in Japan. Of 5 Japanese travelers, 3 were returning from Indonesia, and 2 from Thailand or Malaysia. These results indicate that Aichi virus or a similar agent is endemic in Southeast Asian countries and is a cause of gastrointestinal symptoms in children in these areas or in Japanese travelers who visit there. 相似文献
83.
Various plant organs show a spontaneous curvature on a three-dimensional clinostat. Changes in the cell wall metabolism underlying the curvature were examined in maize shoots. In coleoptile nodes, no differences were detected in either the level or the composition of cell wall polysaccharides between the convex and the concave halves. However, the convex side showed a higher activity of (1 --> 3),(l --> 4)-beta-glucan breakdown, which appears to be associated with the curvature. In the elongating region of coleoptiles, the accumulation of wall polysaccharides occurred in the convex side. There was no significant difference in the glucanase activity between both sides. Thus, the spontaneous curvature in different regions of maize shoots may be brought about through different mechanisms under simulated microgravity conditions. 相似文献
84.
Hemoglobin (Hb) obtained from the hemolysate of normal subjects and diabetic patients was separated into HbA1a1, HbA1a2, HbA1b, HbA1c and HbA0 (major Hb) by Bio-Rex 70 cation exchange column chromatography. The glycosylated Hbs were further separated reproductively by cation exchange high performance liquid chromatography (HPLC), using 50 mM sodium phosphate buffer pH 5.80 with 0-0.2 M NaCl linear gradient system. HbA1b and HbA1c were separated into two subfractions (HbA1b1 and HbA1b2) and three subfractions (HbA1c1, HbA1c2, HbA1c3), respectively. The percentages of each subfraction except HbA1c1 in diabetic patients were significantly higher than those in normal subjects. Furthermore, HbA1c1, HbA1c2 and HbA1c3 correlated well with fasting blood glucose levels in the prior 5 month period, while subfractions in HbA1b revealed no significant correlation with blood glucose levels. The percentages of each subfraction of HbA1c in patients either with diabetic cataracts or with diabetic neuropathy were almost the same as those in the patients without complications. However, the percentages of each of the three groups were markedly higher than those of the normal subjects. These results suggest that glycosylation of hemoglobin in diabetic patients may be increased in various sites of the molecule in parallel with the blood glucose levels during the preceding 4-5 months. 相似文献
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In an attempt to clarify the role of adrenergic receptors in metabolic responses, interaction of norepinephrine with TSH was studied in canine thyroid slices with regard to cyclic AMP levels. Norepinephrine caused a very rapid (within 1 min), but quite transient increase in cyclic AMP levels. The elevation of cyclic AMP levels induced by TSH was markedly inhibited by norepinephrine. Phentolamine, an α-adrenergic blocker, not only prevented the decline of cyclic AMP levels that followed the rise by norepinephrine, but also abolished the norepinephrine effect on the TSH-induced elevation of cyclic AMP levels. Propranolol, a β-adrenergic blocker, exhibited no such effects. These results indicate that the α-adrenergic receptors control cyclic AMP levels in the thyroid gland. 相似文献
88.
Yukio Yamagata Atsunori Yamashita Katsuhiko Inomata 《Origins of life and evolution of the biosphere》1980,10(1):47-50
Di-and tri-glycine were synthesized in 1M aqueous solution of glycine by bubbling for 90 hr with oxygen discharged in the path from an oxygen cylinder. The peptides were also produced by an incubation at 37°C of 2M glycine solution prepared with 75% hydrogen peroxide, and the yields were traced for 200 days. The final yields were about 0.25% and 0.01% for di-and tri-glycine, respectively. The solution at 166 days of incubation was applied to a Sephadex G 10 column, and the fractions around the top of the chromatogram were found to increase the intensity of ninhydrin color about 45 times after hydrolysis, indicating an existence of oligo-glycine. The solutions of 1M glycine and 0.5M diglycine prepared with 30% hydrogen peroxide were incubated at 37°C for 38 days, and di-and tetra-glycine were detected in the yields of 0.12% and 0.33%, respectively. 相似文献
89.
Transformation-defective mutants of Rous sarcoma virus with longer sizes of genome RNA and their highly frequent occurrences.
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Transformation-defective (td) mutants with different sizes of genomic RNA were isolated from the Prague strain of Rous sarcoma virus, subgroup C(PR-C). All six td viruses (tdTYPR-C) isolated from a single UV-irradiated stock of PR-C (clone 2 of TYPR-C) had slightly longer RNA than did the ordinary class b RNA of tdB77 and Rous-associated virus-7. td viruses spontaneously segregated in uncloned TYPR-C also contained genomic RNA of a size similar to tdTYPR-C RNA. On the other hand, two td mutants isolated from another stock of PR-C (LAPR-C) had the class b RNA. Fingerprint analysis confirmed that tdTYPR-C and tdLAPR-C were derived by deletion from clone 2 of TYPR-C and LAPR-C, respectively, and also showed that clone 2 of TYPR-C had sequences in its genome RNA different from those of LAPR-C, although it gave a fingerprinting pattern similar to the latter. These results strongly suggest that differences between the nucleotide sequences in TYPR-C and LAPR-C RNA may result in different extents of deletion. 相似文献
90.
Urine of a fucosidosis patient contained a large amount of fucosyl oligosaccharides and fucose-rich glycopeptides. Six major oligosaccharides were purified by a combination of Bio-Gel P-2 and P-4 column chromatographies and paper chromatography. Structural studies by sequential exoglycosidase digestion and by methylation analysis revealed that their structures were as follows: Fucalpha1 leads to 6GlcNAc, Fucalpha1 leads to 2Galbeta1 leads to 4(Fucalpha1 leads to 3)GlcNAcbeta1 leads to 2Manalpha1 leads to 3Manbeta1 leads to 4GlcNAc, Galbeta1 leads to 4(Fucalpha1 leads to 3)GlcNAcbeta1 leads to 4Manalpha1 leads to 4GlcNAc, Galbeta1 leads to 4(Fucalpha1 leads to3)GlcNAcbeta1 leads to 2Manalpha1 leads to 6Manbeta1 leads to 4GlcNAc, and Galbeta1 leads to 4(Fucalpha1 leads to 3)GlcNAcbeta1 leads to 4Manalpha1 leads to 6Manalpha1 leads to 6Manbeta1 leads to 4GlcNAc. In additon, the structure of a minor decasaccharide was found to be Galbeta1 leads to (Fucalpha1 leads to)GlcNAcbeta1 leads to Manalpha1 leads to [Galbeta1 leads to (Fucalpha1 leads to)GlcNAcbeta1 leads to Manalpha1 leads to]Manbeta1 leads to 4GlcNAc. 相似文献