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排序方式: 共有151条查询结果,搜索用时 46 毫秒
111.
Selpi Christopher H Bryant Graham JL Kemp Janeli Sarv Erik Kristiansson Per Sunnerhagen 《BMC bioinformatics》2009,10(1):451
Background
Some upstream open reading frames (uORFs) regulate gene expression (i.e., they are functional) and can play key roles in keeping organisms healthy. However, how uORFs are involved in gene regulation is not yet fully understood. In order to get a complete view of how uORFs are involved in gene regulation, it is expected that a large number of experimentally verified functional uORFs are needed. Unfortunately, wet-experiments to verify that uORFs are functional are expensive. 相似文献112.
113.
In vivo expansion of functionally integrated GABAergic interneurons by targeted increase in neural progenitors 下载免费PDF全文
114.
Combining protein evolution and secondary structure 总被引:19,自引:9,他引:10
An evolutionary model that combines protein secondary structure and amino
acid replacement is introduced. It allows likelihood analysis of aligned
protein sequences and does not require the underlying secondary (or
tertiary) structures of these sequences to be known. One component of the
model describes the organization of secondary structure along a protein
sequence and another specifies the evolutionary process for each category
of secondary structure. A database of proteins with known secondary
structures is used to estimate model parameters representing these two
components. Phylogeny, the third component of the model, can be estimated
from the data set of interest. As an example, we employ our model to
analyze a set of sucrose synthase sequences. For the evolution of sucrose
synthase, a parametric bootstrap approach indicates that our model is
statistically preferable to one that ignores secondary structure.
相似文献
115.
Marija Cvijović Daniel Dalevi Elizabeth Bilsland Graham JL Kemp Per Sunnerhagen 《BMC bioinformatics》2007,8(1):295
Background
The translational efficiency of an mRNA can be modulated by upstream open reading frames (uORFs) present in certain genes. A uORF can attenuate translation of the main ORF by interfering with translational reinitiation at the main start codon. uORFs also occur by chance in the genome, in which case they do not have a regulatory role. Since the sequence determinants for functional uORFs are not understood, it is difficult to discriminate functional from spurious uORFs by sequence analysis. 相似文献116.
Evolution of the tryptophan synthetase of fungi. Analysis of experimentally fused Escherichia coli tryptophan synthetase alpha and beta chains 总被引:1,自引:0,他引:1
During evolution of fungi, the separate tryptophan synthetase alpha and beta polypeptides of bacteria appear to have been fused in the order alpha-beta rather than the beta-alpha order that would be predicted from the order of the corresponding structural genes in all bacteria. We have fused the tryptophan synthetase polypeptides of Escherichia coli in both orders, alpha-beta and beta-alpha, with and without a short connecting (con) sequence, to explore possible explanations for the domain arrangement in fungi. We find that proteins composed of any of the four fused polypeptides, beta-alpha, beta-con-alpha, alpha-beta, and alpha-con-beta, are highly active enzymatically. However, only the alpha-beta and alpha-con-beta proteins are as active as the wild type enzyme. All four fusion proteins appear to be less soluble in vivo than the wild type enzyme; this abnormal characteristic is minimal for the alpha-con-beta enzyme. The alpha and beta domains of the four fusion polypeptides were not appreciably more heat labile than the wild type polypeptides. Competition experiments with mutant tryptophan synthetase alpha protein, and the fusion proteins suggest that in each fusion protein the joined alpha and beta domains have a functional tunnel connecting their alpha and beta active sites. Three tryptophan synthetase beta'-alpha fusion proteins were examined in which the carboxyl-terminal segment of the wild type beta polypeptide was deleted and replaced by a shorter, unnatural sequence. The resulting deletion fusion proteins were enzymatically inactive and were found predominantly in the cell debris. Evaluation of our findings in relation to the three-dimensional structure of the tryptophan synthetase enzyme complex of Salmonella typhimurium (5) and the results of mutational analyses with E. coli suggest that tryptophan synthetase may have evolved via an alpha-beta rather than a beta-alpha fusion because in beta-alpha fusions the amino-terminal helix of the alpha chain cannot assume the conformation required for optimal enzymatic activity. 相似文献
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Isolation of Saccharomyces cerevisiae TRP3. 总被引:1,自引:1,他引:0
Several plasmids, isolated from two plasmid pools, complemented a Saccharomyces cerevisiae trp3 mutant with defective indole-3-glycerol-phosphate synthase activity. Restriction mapping indicated that a 1.2-kilobase StuI segment was common to all complementing plasmids. Southern blot hybridization established that a cloned 5.2-kilobase BamHI fragment was derived intact from chromosomal DNA. A yeast trp3 mutant transformed with trp3-complementing plasmids contained approximately 40-fold elevated indole-3-glycerol-phosphate synthase activity. These plasmids also complemented an Escherichia coli trpC mutant, and transformants exhibited enzyme activity. Yeast trp3 is therefore associated with a 1.2-kilobase StuI DNA segment. 相似文献