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Kinetics of beta-glucuronidase induction by androgen. Genetic variation in the first order rate constant 总被引:3,自引:0,他引:3
Measurements of enzyme activity, rates of protein synthesis, and mRNA activity suggest that the induction of beta-glucuronidase in mouse kidney in response to androgen is regulated at a pretranslational level. Following an initial lag period, the rate and extent of induction follow the rules of simple turnover kinetics and can be described in terms of a zero order rate constant for acquisition of mRNA activity (ka) and a first order rate constant for loss of activity (kb). Genetic variation in kb, described here for the first time, alters the half-time and extent of induction. Variation in kb is independent of previously described variation in ka and, unlike changes in ka, is not associated with change in the lag time. The DNA sequences determining kb, like those determining ka, are genetically linked to the structural gene for beta-glucuronidase. Following the removal of androgen, beta-glucuronidase activity, rate of synthesis, and mRNA activity all decline rapidly with half-lives of 1-2 days. Even in the most rapidly inducing strains, this is significantly faster than the half-time for induction determined by kb. Furthermore, genetic variation in kb does not affect the rate of de-induction. These facts suggest that kb may not describe the turnover of beta-glucuronidase mRNA, but rather the turnover of another step in the induction process. 相似文献
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S. E. Franklin L. Young D. Watson A. Cigan T. Meyer L. A. Bulla Jr. 《Molecular genetics and genomics : MGG》1997,256(5):517-524
Various subspecies of the gram-positive bacterium Bacillus thuringiensis are known to produce a wide array of insecticidal crystal proteins (ICPs) upon sporulation. These ICPs act primarily on the brush border of midgut epithelial cells of susceptible larvae. Recently, a protein of 210?kDa, isolated from the midgut of Manduca sexta, has been demonstrated to bind the Cry1Ab toxin produced by B. thuringiensis subsp. berliner and is therefore postulated to be involved in mediating the toxicity of Cry1Ab. The cDNA encoding the 210?kDa protein, termed BT-R1 (Bacillus thuringiensis receptor-1), was recently cloned, and shows limited homology to the cadherin superfamily of proteins. Quite naturally, there is a great deal of interest in the characterization of BT-R 1 , the gene encoding the 210?kDa Cry1Ab binding protein. The studies presented here involve the use of various restriction fragments prepared from the cDNA encoding BT-R1 as probes of Southern blots bearing M. sexta genomic DNA cleaved with a variety of restriction endonucleases. These Southern blot data reveal that there are two discrete regions within the M. sexta genome which encode sequences homologous to BT-R1. On the basis of the signal intensities seen on Southern blots, it appears that only one of these genes encodes BT-R1, whereas the other is a closely related homologue. 相似文献
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Effect of carbon source on lysine-mediated inhibition of postexponential growth of Saccharomyces cerevisiae 总被引:1,自引:0,他引:1 下载免费PDF全文
T G Watson 《Journal of bacteriology》1983,154(2):1013-1014
Lysine-mediated inhibition of postexponential growth in Saccharomyces cerevisiae occurred when glucose, fructose, or maltose, but not lactate, pyruvate, or ethanol, was used as the carbon source. Arginine starvation is not responsible for the inhibitory effect, since neither the intracellular pool of glucose-grown (inhibited) cells nor that of lactate-grown (noninhibited) cells contained arginine. 相似文献
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Q Yuan W M Jiang D Hollander E Leung J D Watson G W Krissansen 《Biochemical and biophysical research communications》1991,176(3):1443-1449
A cDNA clone encoding the N-terminal sequence of the murine integrin beta 7 subunit, a novel member of the leukocyte cell adhesion molecule subset (Leu-CAM), has been isolated. An N-terminal region of 13 contiguous amino acids deduced from the cDNA shows complete identity with the N-terminus of the 120 kDa subunit of the M290 antigen, a surface molecule found highly expressed on mouse intestinal intraepithelial lymphocytes (IEL). This unexpected result focuses two previously unconnected areas of research and suggests that integrins may have a special role to play in the defence of the gut mucosa. 相似文献