signal peptide
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- MeSH
- mezibuněčná komunikace MeSH
- receptory peptidů fyziologie MeSH
- signální transdukce MeSH
- Publikační typ
- přehledy MeSH
Insect prophenoloxidases (PPOs) are important immunity proteins for defending against the invading pathogens and parasites. As a Type-III copper-containing proteins, unlike Homo sapiens tyrosinases, the insect PPOs and most bacterial tyrosinases contain no signal peptides for unknown reason, however they can still be released. To this end, we fused different signal peptides to Drosophila melanogaster PPOs for in vitro and in vivo expression, respectively. We demonstrate that an artificial signal peptide can help PPO secretion in vitro. The secreted PPO appeared larger than wild-type PPO on molecular weight sizes due to glycosylation when expressed in S2 cells. Two asparagine residues for potential glycosylation in PPO1 were identified when a signal peptide was fused. After purification, the glycosylated PPO1 lost zymogen activity. When PPO1 containing a signal peptide was over-expressed in Drosophila larvae, the glycosylation and secretion of PPO1 was detected in vivo. Unlike insect PPO, human tyrosinase needs a signal peptide for protein expression and maintaining enzyme activity. An artificial signal peptide fused to bacterial tyrosinase had no influence on the protein expression and enzyme activity. These Type-III copper-containing proteins from different organisms may evolve to perform their specific functions. Intriguingly, our study revealed that the addition of calcium inhibits PPO secretion from the transiently cultured larval hindguts in vitro, indicating that the calcium concentration may regulate PPO secretion. Taken together, insect PPOs can maintain enzyme activities without any signal peptide.
- MeSH
- buněčné linie MeSH
- Drosophila melanogaster * imunologie metabolismus MeSH
- glykosylace MeSH
- hmyzí proteiny metabolismus genetika MeSH
- katecholoxidasa * metabolismus MeSH
- larva metabolismus MeSH
- lidé MeSH
- prekurzory enzymů * metabolismus MeSH
- proteinové prekurzory metabolismus MeSH
- proteiny - lokalizační signály * MeSH
- proteiny Drosophily metabolismus genetika MeSH
- tyrosinasa metabolismus MeSH
- vápník metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Byly charakterizovány změny alfa subjednotek hlavních typů heterotrimerních GTP-vazebných (G) proteinů v CNS nebo imunitním systému po modulaci různými typy antidepresiv (TCA, SSRI) in vitro svyužitím linie C6 gliomových buněk a přirozených zabíječů (NK lymfocytů). Vlivem akutně působícího fluoxetinu byly sníženy hladiny G alfa q/11 subjednotky a 1, 4, 5 inositoltrifosfátu (IP3) jako druhého posla efektorové dráhy regulované fosfolipázou C až po apoptické děje. Byl prokázán vztah mezi profily Galfa subjednotek (G alfa q/11, G alfa s a G alfai1, 2) a typem antidepresiva, zvláště SSRI typu. Rovněž byl studován přenos buněčného signálu ve sledu purinoceptor (adenozinový receptor) – G protein – efektor a možný vztah k působení antidepresiva v modelových reakcích in vitro.
Changes of Galpha subunit levels of main heterotrimeric GTP-binding (G) proteins were characterized in CNS and immune system after antidepressant modulation in vitro using lines of C6 glioma cells and natural killers (NK lymphocytes). We analyzed cell signal transduction induced by acute effect of fluoxetine by decreased Galpha q/11 level and 1, 4, 5 inositoltriphosphate (IP3) as 2nd messenger of effector phospholipase C pathway and modulation of apoptosis. We demonstrated relationship among antidepressant especially of SSRI type and G alpha subunit patterns (G alfa q/11, G alfa s a G alfai1, 2) were demonstrated. Furthermore cell signal transduction via purinoceptor (adenosine receptor) – G protein – effector in relationship to antidepressant effect was studied in model reactions in vitro.
Like all other secretory proteins, the HIV-1 envelope glycoprotein gp160 is targeted to the endoplasmic reticulum (ER) by its signal peptide during synthesis. Proper gp160 folding in the ER requires core glycosylation, disulfide-bond formation and proline isomerization. Signal-peptide cleavage occurs only late after gp160 chain termination and is dependent on folding of the soluble subunit gp120 to a near-native conformation. We here detail the mechanism by which co-translational signal-peptide cleavage is prevented. Conserved residues from the signal peptide and residues downstream of the canonical cleavage site form an extended alpha-helix in the ER membrane, which covers the cleavage site, thus preventing cleavage. A point mutation in the signal peptide breaks the alpha helix allowing co-translational cleavage. We demonstrate that postponed cleavage of gp160 enhances functional folding of the molecule. The change to early cleavage results in decreased viral fitness compared to wild-type HIV.
- MeSH
- buněčné linie MeSH
- HIV obalový protein gp160 chemie metabolismus MeSH
- HIV-1 fyziologie MeSH
- konformace proteinů MeSH
- lidé MeSH
- proteiny - lokalizační signály * MeSH
- proteolýza MeSH
- sbalování proteinů * MeSH
- transport proteinů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
Hepatitis B virus uses e antigen (HBe), which is dispensable for virus infectivity, to modulate host immune responses and achieve viral persistence in human hepatocytes. The HBe precursor (p25) is directed to the endoplasmic reticulum (ER), where cleavage of the signal peptide (sp) gives rise to the first processing product, p22. P22 can be retro-translocated back to the cytosol or enter the secretory pathway and undergo a second cleavage event, resulting in secreted p17 (HBe). Here, we report that translocation of p25 to the ER is promoted by translocon-associated protein complex. We have found that p25 is not completely translocated into the ER; a fraction of p25 is phosphorylated and remains in the cytoplasm and nucleus. Within the p25 sp sequence, we have identified three cysteine residues that control the efficiency of sp cleavage and contribute to proper subcellular distribution of the precore pool.
- MeSH
- cystein metabolismus MeSH
- endoplazmatické retikulum metabolismus MeSH
- hepatitida B - antigeny e * metabolismus MeSH
- hepatitida B * metabolismus MeSH
- lidé MeSH
- membránové glykoproteiny MeSH
- proteiny - lokalizační signály genetika MeSH
- proteiny vázající vápník MeSH
- receptory cytoplazmatické a nukleární MeSH
- receptory peptidů MeSH
- virus hepatitidy B metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
CART (cocaine- and amphetamine-regulated transcript) peptide is a neuropeptide with a powerful central anorexigenic effect. Specific CART peptide binding sites, most likely CART peptide receptors, have been found in PC12 cells. This study further characterizes the CART peptide binding sites in PC12 cells. After differentiation to a neuronal phenotype with nerve growth factor, the number of CART peptide binding sites in PC12 cells tripled. Following dexamethasone treatment, which transforms PC12 cells into chromaffin-like cells, the number of CART peptide binding sites substantially decreased. CART peptide did not affect the differentiation or acetylcholinesterase activity of PC12 cells, indicating that CART peptide does not participate in differentiation or neuronal activity. CART peptide increased the phosphorylation of SAPK/JNK (stress-activated protein kinase/c-Jun-amino-terminal kinase) and subsequent c-Jun protein expression. These effects were reversed by SP600125, a specific JNK-kinase inhibitor. CART peptide did not significantly affect ERK (extracellular signal-regulated kinase), CREB (cAMP responsive element binding protein), or p38 phosphorylation and c-Fos protein expression. Central administration of CART peptide into mice also resulted in increased c-Jun positive cells in dorsomedial hypothalamic nucleus and nucleus of the solitary tract, areas involved in food intake regulation. Activation of c-Jun by CART peptide might indicate a possible role of CART peptide in managing stress conditions rather than a role in cell proliferation or differentiation as well as the more complex and/or specific regulation ways by transcription factors in some nuclei involved in food intake regulation. The characteristics of stress that CART peptide potentially mediates should be further studied.
- MeSH
- acetylcholinesterasa analýza MeSH
- buňky PC12 MeSH
- hypothalamus účinky léků metabolismus MeSH
- krysa rodu rattus MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- nucleus solitarius účinky léků metabolismus MeSH
- proteiny nervové tkáně metabolismus farmakologie MeSH
- receptory peptidů metabolismus MeSH
- signální transdukce fyziologie MeSH
- vazebná místa MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The situation following anti-obesity drug termination is rarely investigated, eventhough a decrease in body weight needs to be sustained. Therefore, this study examined the impact of twice-daily peripheral administration of 5 mg/kg [N-palm-γGlu-Lys11] prolactin-releasing peptide 31 (palm11-PrRP31) in mice with diet-induced obesity (DIO from consuming a high-fat diet) after 28 days of treatment (palm11-PrRP31 group) and after 14 days of peptide treatment followed by 14 days of discontinuation (palm11-PrRP31 + saline group). At the end of the treatment, cumulative food intake, body weight and subcutaneous fat weight/body weight ratio and leptin plasma level were reduced significantly in both the palm11-PrRP31 group and the palm11-PrRP31 + saline group compared to the saline control group. This reduction correlated with significantly increased FOSB, a marker of long-term neuronal potentiation, in the nucleus arcuatus and nucleus tractus solitarii, areas known to be affected by the anorexigenic effect of palm11-PrRP31. Moreover, activation of leptin-related hypothalamic signaling was registered through an increase in phosphoinositide-3-kinase, increased phosphorylation of protein kinase B (PKB, AKT) and enhanced extracellular signal-regulated kinase 1/2 phosphorylation. Besides, lowered apoptotic markers c-JUN N-terminal kinase and c-JUN phosphorylation were registered in the hypothalami of both palm11-PrRP31-treated groups. This study demonstrates that palm11-PrRP31 positively affects feeding and leptin-related hypothalamic signaling, not only after 28 days of treatment but even 14 days after the termination of a 14-day long treatment without the yo-yo effect.
- MeSH
- apoptóza MeSH
- fosforylace MeSH
- hormon uvolňující prolaktin metabolismus MeSH
- hypothalamus metabolismus MeSH
- leptin metabolismus MeSH
- leptinové receptory metabolismus MeSH
- lidé MeSH
- messenger RNA genetika metabolismus MeSH
- myši inbrední C57BL MeSH
- myši obézní MeSH
- neurony metabolismus MeSH
- omezení příjmu potravy krev MeSH
- přijímání potravy MeSH
- signální transdukce * MeSH
- velikost orgánu MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
We study effects of convective transport on a chemical front wave representing a signal propagation at a simple (single layer) epithelium by means of mathematical modeling. Plug flow and laminar flow regimes were considered. We observed a nonmonotonous dependence of the propagation velocity on the ligand receptor binding constant under influence of the convective transport. If the signal propagates downstream, the region of high velocities becomes much broader and spreads over several orders of magnitude of the binding constant. When the convective transport is oriented against the propagating signal, either velocity of the traveling front wave is slowed down or the traveling front wave can stop or reverse the direction of propagation. More importantly, chemical signal in epithelial systems influenced by the convective transport can propagate almost independently of the ligand-receptor binding constant in a broad range of this parameter. Furthermore, we found that the effects of the convective transport becomes more significant in systems where either the characteristic dimension of the extracellular space is larger/comparable with the spatial extent of the ligand diffusion trafficking or the ligand-receptor binding/ligand diffusion rate ratio is high.
Apolipoprotein B (apo B) is the major protein component of LDL, VLDL and chylomicrons. Numerous polymorphisms of the apolipoprotein B gene have been described. Particularly, the insertion/deletion polymorphism located in the coding part of the signal peptide of apo B, associated with modification of lipid concentrations and the risk of cardiovascular disease, has been reported in the general population. No such study in the Tunisian population has been performed. The aim of our study was to assess the effect of insertion/deletion polymorphism of the apolipoprotein B gene on lipid levels in a sample of the Tunisian population. A total of 458 unrelated subjects (321 men and 137 women) were included. The insertion/deletion polymorphism was determined by electrophoresis on polyacrylamide gels after PCR amplification. The relative frequencies of the Ins and Del alleles were 0.74 and 0.26, respectively. These frequencies were similar to those found in other Caucasian populations. There was no significant difference in serum TC, TG, and HDL-C levels due to the influence of the genotypes. However, significant variation among the three genotypes was seen for LDL-cholesterol (p<0.001) and apo B (p<0.001) levels. Individuals homozygous for the Del allele had higher levels than individuals homozygous for the Ins allele, while individuals heterozygous for both alleles exhibited intermediate levels. When the data were analyzed in men and women separately, a similar effect was seen in both groups. Our results show that distribution of apo B insertion/deletion polymorphism in Tunisians is similar to other Caucasian population and confirm the reported association with serum LDL-cholesterol and apo B concentrations.
- MeSH
- apolipoproteiny B genetika krev metabolismus MeSH
- epidemiologické studie MeSH
- financování organizované MeSH
- interpretace statistických dat MeSH
- kardiovaskulární nemoci komplikace MeSH
- LDL-cholesterol genetika krev MeSH
- lipidy genetika krev MeSH
- polymerázová řetězová reakce metody využití MeSH
- polymorfismus genetický genetika MeSH
