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131.
Summary Using two independent techniques, ultracentrifugation in a KBr-gradient, and native pore polyacrylamide gel electrophoresis in combination with [3H]-epoxyfarnesyldiazoacetate photoaffinity labeling, we showed that in the hemolymph ofPeriplaneta americana, and probably also inLeptinotarsa decemlineata JH-III binds to the lipophorin, whereas inLocusta migratoria JH-III binds to a different protein. 相似文献
132.
There is now good evidence that cytoplasmic pH (pHi) may have an important role in the metabolic activation of quiescent cells. In particular, growth stimulation of mammalian fibroblasts leads to a rapid increase in pHi (refs 3-6), due to activation of a Na+/H+ exchanger in the plasma membrane, and this alkalinization is necessary for the initiation of DNA synthesis. However, the mechanism by which mitogens activate the Na+/H+ exchanger to raise pHi is not known, although an increase in cytoplasmic free Ca2+ ([Ca2+]i) has been postulated as the primary trigger. We now present data suggesting that the Na+/H+ exchanger is set in motion through protein kinase C, a phospholipid- and Ca2+-dependent enzyme normally activated by diacylglycerol produced from inositol phospholipids in response to external stimuli. Using newly developed pH microelectrodes and fluorimetric techniques, we show that a tumour promoting phorbol ester and synthetic diacylglycerol, both potent activators of kinase C (refs 12-15), mimic the action of mitogens in rapidly elevating pHi in different cell types. Furthermore, we demonstrate that, contrary to previous views, an early rise in [Ca2+]i is not essential for the activation of Na+/H+ exchange and the resultant increase in pHi. Finally, we suggest that an alkaline pHi shift, mediated by Na+/H+ exchange, may be a common signal in the action of those hormones which elicit the breakdown of inositol phospholipids. 相似文献
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F. B. de Jorge J. A. Petersen A. S. F. Ditadi 《Cellular and molecular life sciences : CMLS》1970,26(1):41-43
Résumé Pendant l'hibernation, leStrophocheilus (Pulmoné, Mollusque) perd de l'eau, du sodium, du calciun, du magnésium, du soufre, du cuivre, du fer et des carbohydrates totaux, mais son taux de potassium et d'iode augmente. En état d'estivation, il y en a perte d'eau, de sodium, de magnésium, de cuivre, de fer et de carbohydrates totaux, mais accumulation de calcium. 相似文献
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S. Barrigón J. Tamargo P. D. Garcia de Jalón 《Cellular and molecular life sciences : CMLS》1978,34(6):770-770
Summary Bunaphtide induces a blockade in the3H-norepinephrine uptake and retention in the isolated guinea-pig left atrium. However, this blockade does not seems to be related with the cardiodepressant effect of the drug. 相似文献
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Carcinogenic nitrosamines formed by drug-nitrite interactions 总被引:3,自引:0,他引:3
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Siemens J Lillo C Dumont RA Reynolds A Williams DS Gillespie PG Müller U 《Nature》2004,428(6986):950-955
Mechanoelectrical transduction, the conversion of mechanical force into electrochemical signals, underlies a range of sensory phenomena, including touch, hearing and balance. Hair cells of the vertebrate inner ear are specialized mechanosensors that transduce mechanical forces arising from sound waves and head movement to provide our senses of hearing and balance; however, the mechanotransduction channel of hair cells and the molecules that regulate channel activity have remained elusive. One molecule that might participate in mechanoelectrical transduction is cadherin 23 (CDH23), as mutations in its gene cause deafness and age-related hearing loss. Furthermore, CDH23 is large enough to be the tip link, the extracellular filament proposed to gate the mechanotransduction channel. Here we show that antibodies against CDH23 label the tip link, and that CDH23 has biochemical properties similar to those of the tip link. Moreover, CDH23 forms a complex with myosin-1c, the only known component of the mechanotransduction apparatus, suggesting that CDH23 and myosin-1c cooperate to regulate the activity of mechanically gated ion channels in hair cells. 相似文献