Fibroin
Mostrando 13-24 de 46 artigos, teses e dissertações.
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13. Assumed initiation site of fibroin gene transcription.
To map the initiation site of fibroin gene transcription on cloned genomic fibroin DNA (pFb29), we looked for precursors of fibroin mRNA, first by applying the hybridization mapping method to the RNA from the posterior silk gland of Bombyx mori. The 6.2-kilobase (kb) DNA fragment used for the assay, from 5.7 kb upstream to 0.5 kb downstream from the cap site
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14. In monkey COS cells only the TATA box and the cap site region are required for faithful and efficient initiation of the fibroin gene transcription.
The DNA sequences necessary for faithful and efficient initiation of transcription of Bombyx mori fibroin gene have been studied in vivo using monkey COS cells and a SV40 origin vector. Transcriptional analysis of 5' deletion genes and of exact substitution genes including a series of single base substitution mutants indicates that the TATA box and the cap r
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15. A contribution of the core-promoter and its surrounding regions to the preferential transcription of the fibroin gene in posterior silk gland extracts.
Complementation of a posterior silk gland (psg) extract to a HeLa cell extract specifically enhances the transcription of the Bombyx mori fibroin gene. To map the regions responsible for this enhancement, the fibroin promoter was dissected and the transcriptional function of each region was analyzed. Besides the upstream promoter element 5' to the TATA box,
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16. Promoter sequence of fibroin gene assigned by in vitro transcription system.
We have shown that the silk fibroin gene from Bombyx mori is faithfully transcribed in an in vitro transcription system of the HeLa cell extract prepared by the method of Manley et al. [Manley, J. L., Fire, A., Cano, A., Sharp, P. A. & Gefter, M. L. (1980) Proc. Natl. Acad. Sci. USA 77, 3855-3859]. Using this system and a series of deletion mutants of fibroi
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17. Cloning of the silk fibroin gene and its flanking sequences.
Thirteen Escherichia coli clones containing the whole or a part of the fibroin gene (16 kilobases long) have been isolated. The starting material was DNA extracted from the posterior silk glands of Bombyx mori. Most clones were obtained from sheared DNA fragments linked by poly(dA)-poly(dT) joints to the plasmid pMB9. One of them includes the 5' end of the f
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18. Discontinuous translation of silk fibroin in a reticulocyte cell-free system and in intact silk gland cells.
Silk fibroin mRNA was translated in a rabbit reticulocyte cell-free system. Addition of tRNA from silk glands was essential for complete translation of the fibroin polypeptide. (Mr approximately 400,000). Synthesis of full-sized product took at least 85 min. In addition to full-size product, a large number of smaller polypeptides were observed upon analysis
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19. Chemical synthesis of the hexanucleotide d(A-C-C-A-G-C) required to isolate fibroin mRNA on an affinity column.
The synthesis of the hexanucleotide d)A-C-C-A-G-C), complementary to the 2 major triplets of fibroin mRNA, using the phosphotriester methodology is described. The protected dinucleotides ((MeO)2Tr)dbzA.anC, ((MeO)2Tr)danC.bzA and ((meO)2Tr)dacG.anC were synthesized; the latter two were detritylated and joined in stepwize fashion to the 1st to form the protec
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20. Structural organization of the P25 gene of Bombyx mori and comparative analysis of its 5' flanking DNA with that of the fibroin gene.
We have cloned a large portion of the P25 gene of Bombyx mori encoding the 25,000 dalton polypeptide which associates with fibroin to constitute the major silk protein. Its structure has been investigated by restriction mapping R-loop analysis, S1 nuclease protection experiments and nucleotide sequencing of the region spanning the 5' end of the gene and its
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21. Participation of the upstream region of the fibroin gene in the formation of transcription complex in vitro.
The addition of exogenous histones has an inhibitory effect on fibroin gene transcription in posterior silk gland extracts. The histones probably disturb a process in complex formation, because when transcription complexes were constructed by preincubation of the templates with the extracts, the inhibitory effect of histones was greatly reduced. Transcriptio
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22. Tissue-specific transcription enhancement of the fibroin gene characterized by cell-free systems.
Six cell-free extracts have been used to characterize the nature of DNA signals and trans-acting factors responsible for the transcription enhancement of the Bombyx mori fibroin gene. The upstream element of the fibroin gene involved in the enhancement can be divided into two regions. The proximal region, -72 to -32, is recognized as a common enhancing signa
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23. 13C NMR of Nephila clavipes major ampullate silk gland.
The major ampullate glands of the spider Nephila clavipes contain approximately 0.2 microliter each of a highly concentrated (approximately 50%) solution of silk fibroin. Therefore, the reservoir of silk in these glands presents an ideal opportunity to observe prefolded conformations of a protein in its native state. To this end, the structure and conformati
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24. DNA superhelicity affects the formation of transcription preinitiation complex on eukaryotic genes differently.
In vitro transcription was reconstituted with HeLa cell transcription factors and RNA polymerase II, which were essentially free from DNA topoisomerase activities. DNA templates with defined negative superhelical densities were tested for transcription activity. Transcription of the Bombyx mori fibroin gene increases and plateaus from templates of increasing