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1.
J Temsamani C Alibert J Tazi M Rucheton J P Capony P Jeanteur G Cathala C Brunel 《Journal of molecular biology》1989,206(3):439-449
Native small nuclear ribonucleoproteins (snRNPs) purified by several conventional procedures or reconstituted in vitro have no ribonuclease activity. However, when these same snRNPs are centrifuged in cesium chloride gradients at low [Mg2+] and in the presence of sarkosyl, an endoribonuclease is unmasked at the density of core particles (i.e. containing only the set of low molecular weight proteins common to all snRNPs), while an inhibitory component is released in soluble form. The nature of this inhibitor was not further investigated and the molecular events underlying this inhibition/activation process remained only a matter of speculation. On the other hand, evidence was obtained that the nuclease activity is carried by B-B' on the basis of its comigration with B-B' as well as with two of their cleavage products after SDS/polyacrylamide gel electrophoresis of snRNP proteins. One was identified by a B-B'-specific monoclonal antibody. Another one, especially prominent and migrating between D and E core proteins, was identified as the N-terminal half of B-B' by microsequence analysis. Although tightly associated with core snRNPs, the activity is not dependent upon the presence of an snRNA. For the time being, the functional significance of this nuclease remains entirely elusive. 相似文献
2.
Litman GW; Rast JP; Shamblott MJ; Haire RN; Hulst M; Roess W; Litman RT; Hinds- Frey KR; Zilch A; Amemiya CT 《Molecular biology and evolution》1993,10(1):60-72
Immunoglobulins are encoded by a large multigene system that undergoes
somatic rearrangement and additional genetic change during the development
of immunoglobulin-producing cells. Inducible antibody and antibody-like
responses are found in all vertebrates. However, immunoglobulin possessing
disulfide-bonded heavy and light chains and domain-type organization has
been described only in representatives of the jawed vertebrates. High
degrees of nucleotide and predicted amino acid sequence identity are
evident when the segmental elements that constitute the immunoglobulin gene
loci in phylogenetically divergent vertebrates are compared. However, the
organization of gene loci and the manner in which the independent elements
recombine (and diversify) vary markedly among different taxa. One striking
pattern of gene organization is the "cluster type" that appears to be
restricted to the chondrichthyes (cartilaginous fishes) and limits
segmental rearrangement to closely linked elements. This type of gene
organization is associated with both heavy- and light-chain gene loci. In
some cases, the clusters are "joined" or "partially joined" in the germ
line, in effect predetermining or partially predetermining, respectively,
the encoded specificities (the assumption being that these are expressed)
of the individual loci. By relating the sequences of transcribed gene
products to their respective germ-line genes, it is evident that, in some
cases, joined-type genes are expressed. This raises a question about the
existence and/or nature of allelic exclusion in these species. The
extensive variation in gene organization found throughout the vertebrate
species may relate directly to the role of intersegmental
(V<==>D<==>J) distances in the commitment of the individual
antibody-producing cell to a particular genetic specificity. Thus, the
evolution of this locus, perhaps more so than that of others, may reflect
the interrelationships between genetic organization and function.
相似文献
3.
Enzymatic labeling of nucleic acids is a fundamental tool in molecular biology with virtually every aspect of nucleic acid
hybridization technique involving the use of labeled probes. Different methods for enzymatic labeling of DNA, RNA and oligonucleotide
probes are available today. In this review, we will describe both radioactive and nonradioactive labeling methods, yet the
choice of system for labeling the probe depends on the application under study. 相似文献
4.
Ekambar R. Kandimalla Jamal Temsamani Sudhir Agrawal 《Nucleosides, nucleotides & nucleic acids》2013,32(3-5):1031-1035
Abstract 2′-O-methylribonucleoside methylphosphonamidites are synthesized and incorporated into oligonucleotides to obtain chimeric antisense oligonucleotides. The resulting oligonucleotide binds to their target RNA/DNA sequences efficiently and stable in a medium containing bovine serum. 相似文献
5.
Day FH Zhang Y Clair P Grabstein KH Mazel M Rees AR Kaczorek M Temsamani J 《Journal of immunology (Baltimore, Md. : 1950)》2003,170(3):1498-1503
Linear peptides (SynB vectors) with specific sequence motifs have been identified that are capable of enhancing the transport of a wide range of molecules into cells. These peptide vectors have been used to deliver exogenous peptides and protein Ags across the cell membrane and into the cytoplasm of cells. Specifically, in vitro analysis indicated that these SynB peptides enhanced the uptake of two 9-mer peptide Ags, NP(147-155) and Mtb(250-258) (T cell epitopes of influenza nucleoprotein and Mycobacterium tuberculosis, respectively) and the M. tuberculosis Ag Mtb8.4 protein, into K562 cells when covalently linked to the respective Ags. Furthermore, selected SynB vectors, when conjugated to these same Ags and used as immunogens, resulted in considerably enhanced Ag-specific CTL responses. Several SynB vectors were tested and resulted in varying levels of cellular uptake. The efficiency of uptake correlated with the ability of the SynB construct to deliver each epitope in vivo and induce specific CTL responses in mice. These data suggest that peptide vectors, such as SynB that transport target Ags across the cell membrane in a highly efficient manner, have significant potential for vaccine delivery. 相似文献
6.
Morphine-6-beta-d-glucuronide (M6G) is an active metabolite of morphine with high analgesic potency despite a low blood-brain barrier (BBB) permeability. The aim of the study was to elucidate its transport mechanism across the BBB. We first checked if M6G was effluxed by the P-glycoprotein (P-gp), as previously reported by others. Second, we investigated the role of anionic transporters like the multidrug resistance-associated protein mrp1 and the glucose transporter GLUT-1. The brain uptake of [14C]M6G was measured by the in situ brain perfusion technique in wild-type and deficient mice [mdr1a(-/-) and mrp1(-/-)], with and without probenecid, digoxin, PSC833 or d-glucose. No difference was found between P-gp and mrp1 competent and deficient mice. The brain uptake of [14C]M6G co-perfused with probenecid in wild-type mice was not significantly different from that found in group perfused with [14C]M6G alone. The co-perfusion of [14C]M6G with digoxin or PSC833 was responsible of a threefold decrease of its uptake in mdr1a competent and deficient mice, suggesting that another transporter than P-gp and sensitive to digoxin and PSC833, may be involved. The co-perfusion of [14C]M6G with d-glucose revealed a threefold decrease in M6G uptake. In conclusion, P-gp and mrp1 are not involved in the transport of M6G at the BBB level in contrast to GLUT-1 and a digoxin-sensitive transporter (probably oatp2), which can actively transport M6G but with a weak capacity. 相似文献
7.
Drin G Cottin S Blanc E Rees AR Temsamani J 《The Journal of biological chemistry》2003,278(33):31192-31201
A great deal of data has been amassed suggesting that cationic peptides are able to translocate into eucaryotic cells in a temperature-independent manner. Although such peptides are widely used to promote the intracellular delivery of bioactive molecules, the mechanism by which this cell-penetrating activity occurs still remains unclear. Here, we present an in vitro study of the cellular uptake of peptides, originally deriving from protegrin (the SynB peptide vectors), that have also been shown to enhance the transport of drugs across the blood-brain barrier. In parallel, we have examined the internalization process of two lipid-interacting peptides, SynB5 and pAntp-(43-58), the latter corresponding to the translocating segment of the Antennapedia homeodomain. We report a quantitative study of the time- and dose-dependence of internalization and demonstrate that these peptides accumulate inside vesicular structures. Furthermore, we have examined the role of endocytotic pathways in this process using a variety of metabolic and endocytosis inhibitors. We show that the internalization of these peptides is a temperature- and energy-dependent process and that endosomal transport is a key component of the mechanism. Altogether, our results suggest that SynB and pAntp-(43-58) peptides penetrate into cells by an adsorptive-mediated endocytosis process rather than temperature-independent translocation. 相似文献
8.
KR Rupesh PL PremKumar Vasanth V Shiva Kumar Seetharaman S Jayachandran 《BMC microbiology》2002,2(1):5-7
Background
Seeds of the legume plant Lathyrus sativus, which is grown in arid and semi arid tropical regions, contain Diamino Propionic acid (DAP). DAP is a neurotoxin, which, when consumed, causes a disease called Lathyrism. Lathryrism may manifest as Neurolathyrism or Osteolathyrism, in which the nervous system, and bone formation respectively, are affected. DAP ammonia lyase is produced by a few microorganisms such as Salmonella typhi, Salmonella typhimurium and Pseudomonas, and is capable of detoxifying DAP. 相似文献9.
10.
A mathematical model is proposed which systematically investigates complex calcium oscillations in pancreatic acinar cells. This model is based on calcium-induced calcium release via inositol trisphosphate receptors (IPR) and ryanodine receptors (RyR) and includes calcium modulation of inositol (1,4,5) trisphosphate (IP3) levels through feedback regulation of degradation and production. In our model, the apical and the basal regions are separated by a region containing mitochondria, which is capable of restricting Ca2+ responses to the apical region. We were able to reproduce the observed oscillatory patterns, from baseline spikes to sinusoidal oscillations. The model predicts that calcium-dependent production and degradation of IP3 is a key mechanism for complex calcium oscillations in pancreatic acinar cells. A partial bifurcation analysis is performed which explores the dynamic behaviour of the model in both apical and basal regions. 相似文献