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51.
Grantley W. Lycett Ashton J. Delauney Wenming Zhao John A. Gatehouse Ronald R. D. Croy Donald Boulter 《Plant molecular biology》1984,3(2):91-96
The sequence of two cDNA clones coding for the whole of the -subunit and most of the -subunit of legumin are presented together with a considerable amount of protein sequence data to confirm the predicted amino acid sequence. A unique feature shown by these cDNAs is the presence of three 56 base pair tandem repeats in the region encoding the C terminal of the polypeptide. The tandem repeats are also exhibited in the predicted polypeptide sequence as three 18 amino acid repeats which contain extremely high proportions of polar, mainly acidic, residues. The new sequences are compared to the previously published sequence of some shorter legumin cDNAs (Nature 295: 76–79). In the region where the sequences overlap, the previous cDNAs differ from the new ones by only a few base substitutions but most of the repeated region is not present though the sequences on either side are. The possibility that the absence of the repeats may reflect the difference between two types of legumin gene, rather than an artefact of the cloning of the cDNAs, is discussed. 相似文献
52.
53.
Ronald I. Clyman Louise Wong Michael A. Heymann Abraham M. Rudolph 《Prostaglandins & other lipid mediators》1978,15(2):325-331
The relative potencies of the prostaglandins A1, A2, E1, E2, F2α and their 15-keto-, 15-keto-13,14-dihydro-, and 13,14-dihydro-metabolites were investigated on isolated lamb ductus arteriosus preparations contracted by exposure to elevated PO2. All the prostaglandins (except PGF2α and its 15-keto-metabolites) relaxed the tissue. However, only PGE1, E2, and their 13,14-dihydro-metabolites, were effective at concentrations below 10−8 M. Therefore, events that alter metabolism of circulating PGs in the perinatal period may have significant effects on the relative patency or closure of the ductus arteriosus. 相似文献
54.
55.
A mature medusa of Velella velella (Linnaeus, 1758) is reportedfor the first time from the North Atlantic; previously adultmedusae were known only from the Mediterranean. This specimen,collected by SCUBA divers, is the largest specimen recordedto date. Distinctive features are: two opposite adaxial-axialpairs of perradial capitate tentacles; two marginal bulbs lackingtentacles; conical manubrium with 4 perradial longitudinal gonads;perradial exumbrellar cnidae tracts; cnidome of stenoteles andmacrobasic euryteles; and zooxanthellae within the subumbrella.Since this specimen was collected near the surface and has zooxanthellae,it is likely that V. velella medusae are epipelagic. 相似文献
56.
Summary In Escherichia coli, the structural gene for purine nucleoside phosphorylase, deoD, is subject to insertional inactivation by prophage . From one such secondary site lysogen, strain SP265, one may isolate deletions that remove all or part of the trpR gene and other genes in the deo-thr sector of the E. coli chromosome. Specialized transducing phages harboring serB
+ and trpR
+ were liberated following induction of SP265. All such phages were N-defective, bio-type pseudolysogens whose DNA persisted in the form of plasmids. A collection of transducing phages, differing in their complement of bacterial DNA, was used to locate cleavage sites for bamHI, SalI, and PvuI within the deoD-trpR region of the E. coli genome. The trpR gene lies within a specific 950 base pair BamHI-PvuI segment.A 1250 base pair BamHI fragment carrying a functional trpR gene was cloned into the amplifiable plasmid pBR322. A single SalI site in this fragment was shown to lie within the trpR gene.In two situations where increased gene dosage might generate elevated amounts of Trp repressor (N-defective trpR
+ pseudolysogens and strains harboring pBR322 trpR
+ plasmids) neither tryptophan auxotrophy, enhanced sensitivity to DL-5-methyltryptophan, nor super repression of the tryptophan biosynthetic enzymes was observed.Journal Paper No. 7426 of the Purdue University Agricultural Experiment Station 相似文献
57.
I. Marta Evans Ronald R. D. Croy Philippa Hutchinson Donald Boulter Peter I. Payne Margaret E. Gordon 《Planta》1979,144(5):455-462
Polyribosomes which have template activity in the wheat germ system have been isolated from developing pea seeds. Some of the translation products have identical mobilities to the vicilin and legumin subunits by SDS-PAGE. Certain products were specifically immunoprecipitated with antisera prepared against purified vicilin and legumin fractions. Various RNA fractions including poly A-rich RNA have also been isolated from polyribosomes and shown to direct the synthesis of polyripeptides whose properties are similar to the storage protein subunits. The results are discussed in relationship to other investigations with seed storage protein biosynthesis in vitro.Abbreviations DTT
dithiothreitol
- SDS-PAGE
SDS-polyacrylamide gel electrophoresis
- TCA
tricarboxylic acid 相似文献
58.
Summary A girl with partial trisomy for the short arm of chromosome 10(p12pter) due to mal chromosome segregation in the father 46,XY,t(7;10)(p22;p12) is described. The major abnormalities in this case are: mottled skin, mid-facial hypoplasia, low percentiles for weight, length, and head circumference, and club feet.To whom offprint requests should be sent 相似文献
59.
Summary The trpB gene of S. typhimurium codes for the bifunctional component II subunit of the AS-PRT complex which catalyzes the first two steps of tryptophan biosynthesis. It has previously been shown that the amino-terminal 40% of the component II molecule possesses the catalytic sites determining glutamine amidotransferase (GAT) activity, demonstrable indirectly by complementation with component I, the product of trpA, in the synthesis of anthranilic acid from chorismic acid and glutamine (AS activity), while its carboxy-terminal 60% possesses the catalytic sites determining anthranilate-PRPP phosphoribosyl transferase (PRT) activity, demonstrable by direct enzymatic assay. Here we further demonstrate the functional independence of the two regions of the component II subunit by providing evidence for the existence of monofunctional (GAT-, PRT+) carboxy-terminal restart fragments of component II in certain chain terminating trpB mutants. Nonsense and frameshift mutants of the operator-proximal portion (region 1) of trpB have been found to grow well in media supplemented with anthranilic acid, implying the presence of PRT activity in the cell. Analysis of extracts of these strains has demonstrated the presence of low, but variable levels of PRT activity, but no GAT activity. Correlation of the map location of these mutations with the intensity of their polar effects on the expression of operator-distal genes suggests the existence of at least two gradients or units of polarity within region 1. Furthermore, in double mutant polarity tests, multiplicatiove polar effects were found in certain region 1 trpB-trpB double mutants strains. Taken together, these results lead us to conclude that at least two sites for reinitiation of translation exist within region 1 of trpB which can be activated by the presence of a nearby chain terminating codon. Such reinitation leads to the synthesis of labile carboxy-terminal restart fragments of component II which possess PRT function, but lack GAT function. 相似文献
60.