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21.
22.
Duga S Asselta R Tenchini ML 《The international journal of biochemistry & cell biology》2004,36(8):1393-1399
The coagulation cascade involves sequential enzymatic activations of serine protease zymogens that converge on the generation of thrombin. Factor V (FV) takes part in this process as a component of the prothrombinase complex. Besides its role as procoagulant factor, it is also involved in the physiologic anticoagulant pathway, by participating in the inactivation of activated factor VIII (FVIIIa). Given the dual role of FV, genetic defects in FV gene may result in opposite hemorrhagic or thrombotic phenotypes. This review focuses on the structure, function (procoagulant and anticoagulant), regulation (activation and inactivation) of FV as well as on the genetic defects associated with mutations in the FV gene. 相似文献
23.
Tenchini ML Savant F Paini C Montefusco MC Donati V Malcovati M 《Cell biology international》2001,25(3):197-204
Cultured epithelial grafts are used in the clinical treatment of both non-healing and acute partial-thickness wounds, owing to their ability to stimulate endogenous re-epithelialization. We have previously demonstrated that during the first 24 h following plating, human epidermal keratinocytes secrete an autocrine-acting mitogenic activity. Since the biological activity of cultured grafts is believed to decrease with cellular age, the effect of both in vivo and in vitro keratinocyte age on the secretion of this mitogenic activity, as well as on responsiveness to this activity, was studied. Keratinocytes from donors ranging in age from 2 to 81 years were analysed at increasing in vitro population doublings. Secretion into the medium of the mitogenic activity was not affected by either in vivo or in vitro cellular ageing, while responsiveness of keratinocytes to this mitogenic activity was age-related. These results suggest that cultured grafts from elderly donors may be effective in wound treatment. 相似文献
24.
The MMS22L–TONSL heterodimer directly promotes RAD51‐dependent recombination upon replication stress 下载免费PDF全文
Wojciech Piwko Karun Mutreja Lepakshi Ranjha Diana Stafa Alexander Smirnov Mia ML Brodersen Ralph Zellweger Andreas Sturzenegger Pavel Janscak Massimo Lopes Matthias Peter Petr Cejka 《The EMBO journal》2016,35(23):2584-2601
Homologous recombination (HR) is a key pathway that repairs DNA double‐strand breaks (DSBs) and helps to restart stalled or collapsed replication forks. How HR supports replication upon genotoxic stress is not understood. Using in vivo and in vitro approaches, we show that the MMS22L–TONSL heterodimer localizes to replication forks under unperturbed conditions and its recruitment is increased during replication stress in human cells. MMS22L–TONSL associates with replication protein A (RPA)‐coated ssDNA, and the MMS22L subunit directly interacts with the strand exchange protein RAD51. MMS22L is required for proper RAD51 assembly at DNA damage sites in vivo, and HR‐mediated repair of stalled forks is abrogated in cells expressing a MMS22L mutant deficient in RAD51 interaction. Similar to the recombination mediator BRCA2, recombinant MMS22L–TONSL limits the assembly of RAD51 on dsDNA, which stimulates RAD51‐ssDNA nucleoprotein filament formation and RAD51‐dependent strand exchange activity in vitro. Thus, by specifically regulating RAD51 activity at uncoupled replication forks, MMS22L–TONSL stabilizes perturbed replication forks by promoting replication fork reversal and stimulating their HR‐mediated restart in vivo. 相似文献
25.
The small-subunit ribosomal RNA gene sequences from the hypotrichous ciliates Oxytricha nova and Stylonychia pustulata 总被引:17,自引:0,他引:17
We have determined the complete nucleotide sequence of the small- subunit
ribosomal RNA genes for the ciliate protozoans Stylonychia pustulata and
Oxytricha nova. The sequences are homologous and sufficiently similar that
these organisms must be closely related. In a phylogeny inferred from
comparisons of several eukaryotic small-subunit ribosomal RNAs, the
divergence of the ciliates from the eukaryotic line of descent is seen to
coincide with the radiation of the plants, the animals, and the fungi. This
radiation is preceded by the divergence of the slime mold, Dictyostelium
discoideum.
相似文献
26.
Effects of EDTA treatment upon the protein subunit composition and mechanical properties of mammalian single skeletal muscle fibers 总被引:9,自引:0,他引:9 下载免费PDF全文
Considerable interest has been focused on the role of myosin light chain LC(2) in the contraction of vertebrate striated muscle. A study was undertaken to further our investigations (Moss, R.L., G.G. Giulian, and M.L. Greaser, 1981, J. Biol. Chem., 257:8588-8591) of the effects of LC(2) removal upon contraction in skinned fibers from rabbit psoas muscles. Isometric tension and maximum velocity of shortening, V(max), were measured in fiber segments prior to LC(2) removal. The segments were then bathed at 30 degrees C for up to 240 min in a buffer solution containing 20 mM EDTA in order to extract up to 60 percent of the LC(2). Troponin C (TnC) was also partially removed by this procedure. Mechanical measurements were done following the EDTA extraction and the readditions of first TnC and then LC(2) to the segments. The protein subunit compositions of the same fiber segments were determined following each of these procedures by SDS PAGE of small pieces of the fiber. V(max) was found to decrease as the LC(2) content of the fiber segments was reduced by increasing the duration of extraction. EDTA treatment also resulted in substantial reductions in tension due mainly to the loss of TnC, though smaller reductions due to the extraction of LC(2) were also observed. Reversal of the order of recombination of LC(2) and TnC indicated that the reduction in V(max) following EDTA treatment was a specific effect of LC(2) removal. These results strongly suggest that LC(2) may have roles in determining the kinetics and extent of interaction between myosin and actin. 相似文献
27.
Nucleotide sequence analysis of the lemur beta-globin gene family: evidence for major rate fluctuations in globin polypeptide evolution 总被引:1,自引:0,他引:1
Lemur beta-related globin genes have been isolated and sequenced. Orthology
of prosimian and human epsilon-, gamma-, and beta-related globin genes was
established by dot-matrix analysis. All of these lemur globin genes
potentially encode functional beta-related globin polypeptides, though
precisely when the gamma-globin gene is expressed remains unknown. The
organization of the 18-kb brown lemur beta-globin gene cluster (5'
epsilon-gamma-[psi eta-delta]-beta 3') is consistent with its evolution by
contraction via unequal crossing-over from the putative ancestral mammalian
beta-globin gene cluster (5' epsilon-gamma- eta-delta-beta 3'). The dwarf
lemur nonadult globin genes are arranged as in the brown lemur. Similar
levels of synonymous (silent) nucleotide substitutions and noncoding DNA
sequence differences have accumulated between species in all of these
genes, suggesting a uniform rate of noncoding DNA divergence throughout
primate beta-globin gene clusters. These differences are comparable with
those observed in the nonfunctional psi eta pseudogene and have therefore
accumulated at the presumably maximal neutral rate. In contrast,
nonsynonymous (replacement) nucleotide substitutions show a significant
heterogeneity in distribution for both the same gene in different lineages
and different genes in the same lineage. These major fluctuations in
replacement but not silent substitution rates cannot be attributed to
changes in mutation rate, suggesting that changes in the rate of globin
polypeptide evolution in primates is not governed solely by variable
mutation rates.
相似文献
28.
29.
Molecular population genetics of ref(2)P, a locus which confers viral resistance in Drosophila 总被引:4,自引:0,他引:4
The ref(2)P locus (2-54.2) is polymorphic for two allelic forms in natural
populations of Drosophila melanogaster, ref(2)Po and ref(2)Pp. The latter
allele confers resistance to the rhabdovirus sigma infecting wild
populations. Previous work, based on a small sample of prescreened
restrictive (resistant) and permissive (susceptible) alleles, identified a
large number of amino acid replacement changes (7) relative to synonymous
changes (1). Such protein variability could be the result of
variation-enhancing selection. To further test the selection hypothesis, we
have examined the DNA sequences of ten randomly chosen lines of D.
melanogaster and one line of D. simulans. Nine of the ten lines are
permissive; D. simulans does not harbor the virus. The melanogaster alleles
contain 4 synonymous changes, 19 noncoding changes, and 13 amino acid
replacement changes, indicating a relatively high level of polymorphism.
Three sequenced restrictive alleles have nearly identical sequences,
indicating that they are relatively young. Compared to the permissive
alleles, they share only a complex deletion at codon 34, CAG-AAT to GGA,
which our analysis indicates to be the site conferring the restrictive
phenotype. Patterns of polymorphism and divergence differ from neutral
predictions by several criteria for the amino terminal region, which
contains the complex deletion (codons 1-91), but not the remainder of the
protein (codons 92-599). We find a higher rate of evolution on the D.
melanogaster lineage than on the D. simulans lineage. The relatively large
amount of both replacement and silent polymorphism in the permissive
alleles and the lack of divergence between permissive and restrictive
alleles suggests that the sigma virus and ref(2)P may be engaged in an
evolutionary race in which new restrictive alleles are continually arising
but are relatively short-lived.
相似文献
30.