Protein synthesis - Biology-Online Dictionary
Protein synthesis is a two-part process that involves a second type of nucleic acid along with DNA.
Protein Synthesis -Translation and Regulation
Ghosh JC, Siegelin MD, Dohi T and AltieriDC: Heat shock protein 60 regulation of the mitochondrialpermeability transition pore in tumor cells. Cancer Res.70:8988–8993. 2010. : :
Consistently with the observation by Sciacovelli (), Yoshida () showed that TRAP1downregulates mitochondrial respiration and ATP production. TRAP1KO mouse adult fibroblasts (MAFs) displayed a higher basal OCR anda significantly higher maximum respiratory capacity than wild-type(WT) cells, accompanied by decreased glycolysis. This effect wasTRAP1-dependent, since re-introduction of TRAP1 in MAFs wassufficient to restore basal OCR levels, confirming a preference foroxidative phosphorylation over aerobic glycolysis in TRAP1 KOcells. In agreement, TRAP1 KO cells showed reduced levels ofglycolytic metabolites, increased levels of TCA cycle intermediatesand anaplerotic substrates, and increased fatty acid oxidation andNAD/NADH ratio, confirming a metabolic flux through theTCA cycle independent of glucose metabolism. Increased complex IVenzymatic activity was found in TRAP1 KO cells as well assteady-state ATP levels that was significantly higher than in WTcells. These results were confirmed in HeLa and HCT116 human cancercell lines. In agreement with previous reports, TRAP1-dependentinhibition of mitochondrial respiration resulted in reduced ROSlevels in both MAFs and HCT116, which proves that TRAP1 KO cellsare constitutively exposed to elevated oxidative stress. Sinceelevated ROS favor cell invasion, the authors showed that indeedTRAP1 KO or transient suppression dramatically enhance cellinvasiveness, both in mouse fibroblasts and in a variety of humancell lines. Importantly, this phenotype is sensitive to c-Srcinhibition and ROS scavenging, supporting a direct link betweenTRAP1 deficiency, elevated ROS, and c-Src activation in mediatingthis process. These authors postulated that the impact of TRAP1 onmitochondrial respiration is mediated, at least in part, by itsdirect regulation of mitochondrial c-Src. In fact, a reciprocalregulation of the two proteins was observed, which led to increasedTyr-416 phosphorylation of mitochondrial c-Src upon TRAP1suppression, paired with a preferential interaction of TRAP1 withthe inactive form of c-Src.
Where does protein synthesis occur? | Yahoo Answers
A role of TRAP1 in the protection from apoptosis andits consequent involvement in the onset and maintenance of tumorphenotypes was firstly and elegantly described by Kang (). These authors discovered thatonly tumor cells organize a mitochondrial chaperone network, whichinvolves HSP90, its homolog TRAP1 and the immunophilin cyclophilinD (CypD) in a physical complex that regulates permeabilitytransition pore (PTP) opening, maintaining mitochondrialhomeostasis and antagonizing the function of CypD in permeabilitytransition. Considering the high ‘druggability’ of HSP90 ATPasepocket, Kang and colleagues developed a mitochondria-directedvariant of 17-AAG carrying the (calledShepherdin) that efficiently accumulates inside the mitochondria,binds mitochondrial TRAP1 and HSP90, and inhibits their chaperoneactivity via an ATP competition mechanism, thus resulting inCypD-mediated cell death. These observations labelled TRAP1 as anessential controller of mitochondrial homeostasis in tumor cells,conferring them resistance to apoptosis and a survival advantageover the normal counterpart ().The cytoprotective effect of TRAP1 was further investigated by ourgroup through the identification and functional characterization ofTRAP1 interaction with the novel mitochondrial isoform of Sorcin,this providing the first demonstration of a new antiapoptoticcomplex ().
TRAP1 role in cell death protection, beyond thedirect control of PTP opening in concert with HSP90 and CypD evenfurther characterized by other studies (,),may involve some other more general homeostatic mechanisms, linkingthe control of proteostasis inside mitochondria to the activationof extramitochondrial survival pathways. In this context, we haveshown that TRAP1 function could be relevant in crosstalk betweenmitochondria and other subcellular compartments (). Accordingly, the HSP90 mitochondrialnetwork contributes to the folding of mitochondrial proteins;however, when this process is dysregulated, a series ofcytoprotective/adaptive cellular responses occurs, includingactivation of autophagy, inter-organelle stress response andinduction of gene expression modifications, that lead to theimpairment of tumor cell bioenergetics (). These processes may further increasethe apoptotic threshold in tumor cells undergoing mitochondriotoxicstress, ending up with better survival. This adaptive model ishighly suitable to enhance the protein buffering capacity oftransformed cells, which are especially at risk of proteotoxicstress for their high biosynthetic requirements.
10/04/2011 · Where does protein synthesis occur
TRAP1 is involved in proteinhomeostasis. TRAP1 regulates protein expression by couplingsynthesis and ubiquitin-dependent degradation, through a directbinding to both ribosomes and the proteasomal particle TBP7, atER-mitochondria interface. ER, endoplasmic reticulum; M,mitochondrion; C, cytosol.
Recently our group unraveled that this regulatorymechanism is quite complex and involves the modulation ofphosphorylation levels, either in basal conditions or under stress,of the translation factor eIF2α, whose phosphorylation results inthe attenuation of cap-dependent translation, while favoring theIRES-dependent one. TRAP1 slows the rate of protein synthesisthrough the eIF2α pathway, favoring the activation of GCN2 and PERKkinases, with consequent phosphorylation of eIF2α and attenuationof cap-dependent translation. This enhances the synthesis ofselective stress-responsive proteins, as the transcription factorATF4 and its downstream effectors BiP/Grp78 and the cystineantiporter system xCT, thereby providing protection toward ERstress, oxidative damage and nutrient deprivation. Accordingly,TRAP1 silencing sensitizes cells to apoptosis induced by novelantitumoral drugs that inhibit cap-dependent translation, such asRibavirin or 4EGI-1, and reduces the ability of cells to migratethrough the pores of transwell filters in the presence of thesedrugs (). The relevance ofthese findings is supported by evidence that translational controlis a crucial component of cancer development and progression,involved in the regulation of both global protein synthesis andtranslation of selective mRNAs species that promote tumor cellsurvival, angiogenesis, transformation, invasion and metastasis().
Protein synthesis occurs in the cytoplasm on ribosomes
DNA contains information for protein synthesis in cells
mRNA carries the information from the nucleus to the cytoplasm, which is where protein synthesis occurs.
Does protein synthesis occur in the nucleus? | Request …
Protein synthesis occurs on ribosomes in the cytoplasm of a cell but is controlled by DNA located in the nucleus....
When does protein synthesis occurs?
Some ER has ribosomes on the surface (rough endoplasmic reticulum) --the cell's protein-making machinery.
Does protein synthesis occur in the nucleus? - ScienceDirect
Takamura () showed that TRAP1 KD in neuroblastomacells and glioma cancer cell lines of neuronal derivation inducedan abnormal mitochondrial morphology, through a significantdecrease in dynamin-related protein 1 (Drp1) and mitochondrialfission factor (Mff), affecting mitochondrial function. Theseobservations confirm a role of TRAP1 in maintaining mitochondrialmorphology.
where protein synthesis occurs, ..
This review aims at presenting an updated view ofthis important protein mainly in tumor cell pathophysiology. In ouropinion, the core result of recent advances in TRAP1 biology liesin two items of evidence: TRAP1 crucially influences the switchfrom oxidative metabolism to glycolysis, and therefore contributesto tumorigenesis by inhibiting mitochondrial respiration, andsimultaneously affects global protein quality control bycontributing to protein synthesis regulation in the ER. This isrealized through another focused metabolic switch between prevalentcap- to IRES-dependent translation and the balance between proteinsynthesis and cotranslational degradation.
Initiation of Protein Synthesis in Bacteria
Changes in mitochondrial morphology, which isregulated by continuous fusion and fission to form highly connectednetworks or fragmented units, may lead to the degradation ofmitochondria via autophagy (so-called mitophagy) and often causeneuronal synaptic loss and cell death in several humanneurodegenerative diseases. Therefore, cells have developed complexquality control mechanisms to cope with the different challengesconstantly imposed on the integrity of mitochondria. Pridgeon () have indirectlylinked TRAP1 to Parkinson’s disease, demonstrating that PINK1, amajor kinase whose mutations are involved in the development ofautosomic recessive forms of PD, is a binding partner of TRAP1,phosphorylates it upon induction of oxidative stress, and thatTRAP1 is required for PINK1-mediated protection againstoxidative-stress-induced apoptosis.
Protein biosynthesis occurs on large macromolecular ..
Our group was among the first to demonstrate TRAP1involvement in stress-adaptive response of cancer cells: highlevels of both TRAP1 mRNA and protein were found in Saos-2osteosarcoma cells chronically adapted to mild oxidative conditions(). Even more interestingly, weidentified TRAP1 as a key target in the previously hypothesizedcorrelations between resistance to antitumor agents and adaptationto oxidative stress (OS), since very high levels of this proteinwere analogously found in tumor cells resistant to 5-fluorouraciland to platin derivatives. However, the most striking data camefrom the observation that TRAP1 interference, as well as the use ofdominant negative mutants of TRAP1, sensitized OS/chemoresistantcells to cell death inducers, thus supporting the hypothesis ofcommon mechanisms shared by chemoresistance and adaptation to OSand providing the first evidence that TRAP1 is an important playerin the development and the maintenance of these phenotypes. Indeed,TRAP1 hyperexpressing cells show a decreased cleavage of theapoptotic markers Caspase 3 and PARP, and increased levels of thescavenging tripeptide GSH. Hence, TRAP1 may be considered areliable tool to investigate the correlations between oxidativestress, resistance to apoptosis and chemoresistance (,).
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