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71.
Structural analysis of the mouse mdr1a (P-glycoprotein) promoter reveals the basis for differential transcript heterogeneity in multidrug-resistant J774.2 cells. 总被引:5,自引:2,他引:3 下载免费PDF全文
S I Hsu D Cohen L S Kirschner L Lothstein M Hartstein S B Horwitz 《Molecular and cellular biology》1990,10(7):3596-3606
72.
Position effects on the timing of replication of chromosomally integrated simian virus 40 molecules in Chinese hamster cells. 总被引:2,自引:1,他引:1 下载免费PDF全文
Simian virus 40 (SV40) DNA molecules chromosomally integrated at different sites in three Chinese hamster lung fibroblast lines replicated during the middle portion of S phase but not precisely at the same time in all three cell lines. The time of replication was unrelated to the presence of T antigen or to its relative activity in promoting SV40 replication. SV40 sequences and chromosomal DNA sequences adjacent to the SV40 insert in one cell line expressing a temperature-sensitive T antigen showed a T-antigen-independent difference in replication timing from the homologous, allelic locus not linked to SV40. Our results indicate that the timing of replication of these integrated SV40 molecules is dependent upon the site of integration and is not determined by the level of T antigen replication-promoting activity. 相似文献
73.
I. Lerer S. Cohen M. Chemke A. Sanilevich J. Rivlin A. Golan J. Yahav A. Friedman D. Abeliovich 《Human genetics》1990,85(4):416-417
Summary We have analysed the distribution of the ΔF508 mutation and the haplotypes of cystic fibrosis (CF) bearing chromosomes among
the Israeli CF population. The population was classified according to its ethnic origin and included 3 groups, Ashkenazi Jews,
Sephardic/Oriental Jews and Arabs. Haplotype B (KM19 allele 2, XV2c allele 1) was found to be the predominant haplotype in
all groups but in each of them the haplotype distribution was different. The ΔF508 mutation was present in all groups and
accounts for 32% of the CF mutations. It was mainly associated with the B haplotype but only one third of the CF chromosomes
with this haplotype carry the ΔF508 mutation.
This work is dedicated to Dr. Ruth Voss who initiated the CF study in Israel and was tragically killed in a car accident on
7 August 1988 相似文献
74.
Evolution of isopenicillin N synthase genes may have involved horizontal gene transfer 总被引:3,自引:0,他引:3
G Landan G Cohen Y Aharonowitz Y Shuali D Graur D Shiffman 《Molecular biology and evolution》1990,7(5):399-406
The isopenicillin N synthase genes from three fungal species, three Gram-positive species, and one Gram-negative bacterial species share an unusually high sequence similarity. A phylogenetic analysis was carried out to determine which type of evolutionary scenario best accounts for this similarity. The most plausible scenario is one in which a horizontal gene-transfer event, from the prokaryotes to the eukaryotes, occurred at a time close to the divergence between the Gram-positive and the Gram-negative bacteria. 相似文献
75.
A simultaneous increase is found in the level of protein synthesis and the major regulatory glycolytic enzyme, phosphofructokinase (PFK), in early phytohemagglutinin exposure of human lymphocytes. The induction of DNA synthesis is demonstrated to be a much later event. This indicates that the increase of glycolysis in mitogen-stimulated cells precedes cell proliferation, but occurs simultaneously with a general increase in protein synthesis. Chemical inhibitors are used to clarify the interrelationship of protein synthesis, glycolytic enzymes levels, and DNA synthesis. Inhibition of protein synthesis with cycloheximide in the mitogen-exposed lymphocytes prevents any increase in PFK levels, implicating protein synthesis as a cause for the increased glycolysis. Cycloheximide also prevents entry into S phase in mitogen-stimulated lymphocytes which may be due to inhibition of the synthesis of enzymes necessary for DNA synthesis, such as DNA polymerase. Aphidicolin, a specific DNA polymerase inhibitor, is found to have no effect on the increase in protein synthesis and PFK levels that precedes DNA synthesis. The increase in glycolysis in mitogen-stimulated lymphocytes occurs simultaneously with, and is dependent upon, increased protein synthesis, and precedes DNA synthesis and lymphocyte proliferation; thus, the high glycolytic rate of mitogen-stimulated cells is not merely a secondary manifestation of rapid cell proliferation as has been previously reported. 相似文献
76.
77.
Neurite outgrowth in response to transfected N-CAM changes during development and is modulated by polysialic acid 总被引:32,自引:0,他引:32
We have used monolayers of control 3T3 cells and 3T3 cells transfected with a cDNA encoding human N-CAM as a culture substrate for embryonic chick retinal ganglion cells (RGCs). At embryonic day 6 (E6), but not at E11, RGCs extended longer neurites on monolayers of N-CAM-transfected cells. This loss of RGC responsiveness was not associated with substantial changes in the level of N-CAM expression on RGC growth cones. The neurite outgrowth response from E6 RGCs could be inhibited by removal of N-CAM from the monolayer, by removal of alpha 2-8-linked polysialic acid from neuronal N-CAM, or by antibodies that bind exclusively to chick (neuronal) N-CAM. In contrast, the response was not dependent on neuronal beta 1 integrin function. These data provide substantive evidence for a homophilic binding mechanism directly mediating N-CAM-dependent neurite outgrowth, and suggest that changes in polysialic acid expression on neuronal N-CAM may modulate N-CAM-dependent axonal growth during development. 相似文献
78.
Okadaic acid: a new probe for the study of cellular regulation 总被引:92,自引:0,他引:92
The tumour promoter okadaic acid is a potent and specific inhibitor of protein phosphatases 1 and 2A. Here we review recent studies which demonstrate that this toxin is extremely useful for identifying biological processes that are controlled through the reversible phosphorylation of proteins. 相似文献
79.
Isolation and structural analysis of a peptide containing the novel tyrosyl-glucose linkage in glycogenin. 总被引:5,自引:0,他引:5 下载免费PDF全文
The glucosylation site on glycogenin, the protein primer required for de novo glycogen synthesis, has been identified. The glucose is attached at position C1 in a glycosidic linkage with a unique tyrosine, and the sequence surrounding this residue was found to be: His-Leu-Pro-Phe-Ile-Tyr-Asn-Leu-Ser-Ser-Ile-Ser-Ile-Tyr(Glc)-Ser-Tyr-Leu -Pro- Ala-Phe-Lys. The same tyrosine residue is glycosylated whether glycogenin is isolated as a complex with the catalytic subunit of glycogen synthase, or covalently attached to glycogen. The possibility that insulin and growth factors may enhance glycogen synthesis via stimulation of the priming reaction is discussed. 相似文献
80.
Three-dimensional structure of the regular surface glycoprotein layer of Halobacterium volcanii from the Dead Sea 总被引:2,自引:0,他引:2 下载免费PDF全文
A three-dimensional reconstruction from electron micrographs of negatively stained cell envelopes of Halobacterium volcanii has revealed the structure of the surface glycoprotein to a resolution of 2 nm. The glycoprotein is arranged on a p6 lattice with a lattice constant of 16.8 nm. It forms 4.5 nm high, dome-shaped, morphological complexes with a narrow pore at the apex opening into a `funnel' towards the cell membrane. The polarity of the structure was derived from freeze-etching experiments and `edge' views. Six radial protrusions emanate from each morphological complex and join around the 3-fold axis to provide lateral connectivity. Using the primary structure of the surface glycoprotein of the closely related species Halobacterium halobium (Lechner and Sumper, 1987) and the cell envelope profile from a previous X-ray analysis of the same species (Blaurock et al., 1976) we have integrated our reconstruction into a model of halobacterial cell envelope. 相似文献