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51.
Mitochondrial heat-shock protein hsp60 is essential for assembly of proteins imported into yeast mitochondria 总被引:107,自引:0,他引:107
M Y Cheng F U Hartl J Martin R A Pollock F Kalousek W Neupert E M Hallberg R L Hallberg A L Horwich 《Nature》1989,337(6208):620-625
A nuclear encoded mitochondrial heat-shock protein hsp60 is required for the assembly into oligomeric complexes of proteins imported into the mitochondrial matrix. hsp60 is a member of the 'chaperonin' class of protein factors, which include the Escherichia coli groEL protein and the Rubisco subunit-binding protein of chloroplasts. 相似文献
52.
Cloning of decay-accelerating factor suggests novel use of splicing to generate two proteins 总被引:9,自引:0,他引:9
Decay-accelerating factor (DAF), a glycoprotein that is anchored to the cell membrane by phosphatidylinositol, binds activated complement fragments C3b and C4b, thereby inhibiting amplification of the complement cascade on host cell membranes. Here, we report the molecular cloning of human DAF from HeLa cells. Analysis of DAF complementary DNAs revealed two classes of DAF messenger RNA, one apparently derived from the other by a splicing event that causes a coding frameshift near the C terminus. The apparent 'intron' sequence contains an Alu family member and encodes contiguous protein sequence. Two DAF proteins are therefore possible, having divergent C-terminal domains which differ in their hydrophobicity. Both mRNAs are found on polysomes, suggesting that both are translated. We propose that the major (90%) spliced DAF mRNA encodes membrane-bound DAF whereas the minor (10%) unspliced DAF mRNA may encode secreted DAF and we present expression data supporting this. The deduced DAF sequence contains four repeating units homologous to a consensus repeat found in a recently described family of complement proteins. 相似文献
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Given a set of pairwise distances on a set of n points, constructing an edgeweighted tree whose leaves are these n points
such that the tree distances would mimic the original distances under some criteria is a fundamental problem. One such criterion
is to preserve the ordinal relation between the pairwise distances. The ordinal relation can be of the form of total order
on the distances or it can be some partial order specified on the pairwise distances. We show that the problem of finding
a weighted tree, if it exists, which would preserve the total order on pairwise distances is NP-hard. We also show the NP-hardness
of the problem of finding a weighted tree which would preserve a particular kind of partial order called a triangle order,
one of the most fundamental partial orders considered in computational biology. 相似文献
57.
The extent of linkage disequilibrium in Arabidopsis thaliana. 总被引:20,自引:0,他引:20
Magnus Nordborg Justin O Borevitz Joy Bergelson Charles C Berry Joanne Chory Jenny Hagenblad Martin Kreitman Julin N Maloof Tina Noyes Peter J Oefner Eli A Stahl Detlef Weigel 《Nature genetics》2002,30(2):190-193
Linkage disequilibrium (LD), the nonrandom occurrence of alleles in haplotypes, has long been of interest to population geneticists. Recently, the rapidly increasing availability of genomic polymorphism data has fueled interest in LD as a tool for fine-scale mapping, in particular for human disease loci. The chromosomal extent of LD is crucial in this context, because it determines how dense a map must be for associations to be detected and, conversely, limits how finely loci may be mapped. Arabidopsis thaliana is expected to harbor unusually extensive LD because of its high degree of selfing. Several polymorphism studies have found very strong LD within individual loci, but also evidence of some recombination. Here we investigate the pattern of LD on a genomic scale and show that in global samples, LD decays within approximately 1 cM, or 250 kb. We also show that LD in local populations may be much stronger than that of global populations, presumably as a result of founder events. The combination of a relatively high level of polymorphism and extensive haplotype structure bodes well for developing a genome-wide LD map in A. thaliana. 相似文献
58.
Superoxide activates mitochondrial uncoupling proteins. 总被引:64,自引:0,他引:64
Karim S Echtay Damien Roussel Julie St-Pierre Mika B Jekabsons Susana Cadenas Jeff A Stuart James A Harper Stephen J Roebuck Alastair Morrison Susan Pickering John C Clapham Martin D Brand 《Nature》2002,415(6867):96-99
Uncoupling protein 1 (UCP1) diverts energy from ATP synthesis to thermogenesis in the mitochondria of brown adipose tissue by catalysing a regulated leak of protons across the inner membrane. The functions of its homologues, UCP2 and UCP3, in other tissues are debated. UCP2 and UCP3 are present at much lower abundance than UCP1, and the uncoupling with which they are associated is not significantly thermogenic. Mild uncoupling would, however, decrease the mitochondrial production of reactive oxygen species, which are important mediators of oxidative damage. Here we show that superoxide increases mitochondrial proton conductance through effects on UCP1, UCP2 and UCP3. Superoxide-induced uncoupling requires fatty acids and is inhibited by purine nucleotides. It correlates with the tissue expression of UCPs, appears in mitochondria from yeast expressing UCP1, and is absent in skeletal muscle mitochondria from UCP3 knockout mice. Our findings indicate that the interaction of superoxide with UCPs may be a mechanism for decreasing the concentrations of reactive oxygen species inside mitochondria. 相似文献
59.
A survey of expressed genes in Caenorhabditis elegans. 总被引:29,自引:0,他引:29
R Waterston C Martin M Craxton C Huynh A Coulson L Hillier R Durbin P Green R Shownkeen N Halloran 《Nature genetics》1992,1(2):114-123
As an adjunct to the genomic sequencing of Caenorhabditis elegans, we have investigated a representative cDNA library of 1,517 clones. A single sequence read has been obtained from the 5' end of each clone, allowing its characterization with respect to the public databases, and the clones are being localized on the genome map. The result is the identification of about 1,200 of the estimated 15,000 genes of C. elegans. More than 30% of the inferred protein sequences have significant similarity to existing sequences in the databases, providing a route towards in vivo analysis of known genes in the nematode. These clones also provide material for assessing the accuracy of predicted exons and splicing patterns and will lead to a more accurate estimate of the total number of genes in the organism than has hitherto been available. 相似文献
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