Cellular compartment

About: Cellular compartment is a research topic. Over the lifetime, 1082 publications have been published within this topic receiving 53794 citations. The topic is also known as: cell compartmentation.

Cloning and characterization of Vear, a novel Golgi-associated protein involved in vesicle trafficking

Abstract: The control and maintenance of the character, number and protein, carbohydrates and lipid composition of intracellular compartments in a changing environment is one of the fundamental features of a living cell. It is effected, to a large measure, by vesicular traffic which connects the various cellular compartments and handles the transportation of cargo between them. Movement of cargo occurs through a transport system in membrane-bounded containers called vesicles. Vesicles originate at the donor membrane from which they are transported to target organelles where they fuse with the acceptor membrane and deliver their cargo. At the donor site, cytosolic coat proteins or 'coats' bind to the donor membrane together with GTP (guanosine 5'-triphosphate)-binding regulatory proteins first to deform a bud, which is then pinched off as a coated vesicle. During budding and targeting events, a number of regulatory proteins interact with the coat components. Currently, several different coat proteins and their adaptor proteins are known. The purpose of this study was to characterize novel components participitating in intracellular vesicle transport. By using computer analysis and EST (expressed sequence tag) database searches, a previously unknown protein was found. Sequencing revealed the presence of a novel protein of 613 amino acids with a calculated molecular mass of 67,149 Da. Based on its structural features, possessing both a VHS domain and an "ear" domain, we named the protein Vear. With its VHS domain in its NH2 terminus, Vear shows similarity to several endocytosisassociated proteins. With the "ear" domain in its C-terminus, it resembles γ-adaptin, a heavy subunit of the AP-1 complex. Vear mRNA showed a widespread distribution in tissues, with high amounts of mRNA in the kidney, skeletal muscle, and cardiac muscle. At the subcellular level, Vear was localized to the Golgi complex in which it colocalized with the trans-Golgi marker γ-adaptin. The preferential membrane-association was demonstrated by subcellular fractionation in which Vear partitioned with the total membrane fraction. Golgi-associated subcellular localization for Vear was sensitive to a treatment with the fungal metabolite brefeldin A, suggesting an ARF (ADP-ribosylation factor)-dependent recruitment onto membranes. In transfection studies, the full-length Vear assembled on and caused structural "compaction" of the Golgi complex, while overexpression of the "ear" domain alone showed diffuse Golgi-localization without "compaction". The VHS domain, on the other hand, was mainly vesicleand plasma membrane associated and did not show any association with Golgi. In skeletal muscle, Vear was detected preferentially in type I cells by immunohistochemistry and immunofluorescence microscopy. In normal kidney, Vear was exclusively present in glomerular epithelial cells (podocytes) and Vear protein was expressed in a developmentally regulated manner during glomerulogenesis. By immunolabeling electron microscopy, Vear was seen in vesicular and membrane structures adjacent to the Golgi complex. Vear was also abundant in the gastrointestinal tract in cells active in secretion. The results indicate that Vear is a novel vesicle transport-associated protein, detected mainly in the Golgi complex and localized in tissues in a highly cell-type specific manner.

Reduced temperature does not prevent transport of lysosomal integral membrane proteins from endoplasmic reticulum and through the Golgi system to lysosomes.

Abstract: The effect of low temperature on the transport of three lysosomal integral membrane proteins (I, II and III) from endoplasmic reticulum to lysosomes has been studied in normal rat kidney cells. At 15°C and 18°C, though slowly, the proteins could leave the endoplasmic reticulum, move through the Golgi system from the cis to the trans side, and accumulate in lysosomes. Transport of these proteins at low temperature occurred slower than at 37°C. Both at low temperature and 37°C, the proteins were transported between the endoplasmic reticulum and Golgi (III > I and II) and from Golgi to lysosomes (II > III > > I) with different rates.

How to obtain the organelles of prokaryotic and microbial eukaryotic cells

Abstract: An organelle is a specialized functional subunit within cells carrying out specific functions. These compartments which may or may not be enclosed in a lipid bilayer are found in microorganisms. While those found in eukaryotic cells are usually enclosed in lipid bilayer, those in prokaryotes don’t. All microbes have compartments common to them like the nucleic acids, protein, ribosomes as well as unique intracellular structures found only in microbial subgroups. Such compartments include the mitochondria, endoplasmic reticulum, golgi apparatus amongst others unique to all eukaryotic cells only. Prokaryotes contain some micro-compartments unique to them including the carboxysomes, lipid bodies, polyhydroxybutyrate granules. The right choice of cell disruption methods that limit damage to the compartments is important in achieving successful compartment isolation and purification. Commonly applied methods include sonication, enzymatic lysis, detergent lysis, cavitation amongst others depending on the type of cells involved. Fractionation is the commonly utilized method for isolation and purification of organelles, utilizing ultracentrifugation and techniques that exploits size, density and surface charge variations of protoplasmic content. Such techniques include gradient centrifugation methods, use of beads, affinity purification chromatography methods and electrophoresis. Here, we review the compartments in microbial cells and the techniques employed to isolate and purify these intracellular components. Key words: cell disruption, purification, prokaryote, eukaryote, functional unit.

Identification of a truncated form of methionine sulfoxide reductase a expressed in mouse embryonic stem cells

Abstract: Methionine Sulfoxide Reductase A (MsrA), an enzyme in the Msr gene family, is important in the cellular anti-oxidative stress defense mechanism. It acts by reducing the oxidized methionine sulfoxide in proteins back to sulfide and by reducing the cellular level of reactive oxygen species. MsrA, the only enzyme in the Msr gene family that can reduce the S-form epimers of methionine sulfoxide, has been located in different cellular compartments including mitochondria, cytosol and nuclei of various cell lines. In the present study, we have isolated a truncated form of the MsrA transcript from cultured mouse embryonic stem cells and performed eGFP fusion protein expression, confocal microscopy and real time RT-PCR studies. Results show a different expression response of this truncated transcript to oxygen deprivation and reoxygenation treatments in stem cells, compared to the longer full length form. In addition, a different subcellular localization pattern was noted with most of the eGFP fusion protein detected in the cytosol. One possibility for the existence of a truncated form of the MsrA transcripts could be that with a smaller protein size, yet retaining a GCWFG action site, this protein might have easier access to oxidize methionine residues on proteins than the longer form of the MsrA protein, thus having an evolutionary selection advantage. This research opens the door for further study on the role and function of the truncated MsrA embryonic mouse stem cells.

Multiple cellular compartments engagement in Nicotiana benthamiana-peanut stunt virus-satRNA interactions revealed by systems biology approach.

Abstract: PSV infection changed the abundance of host plant’s transcripts and proteins associated with various cellular compartments, including ribosomes, chloroplasts, mitochondria, the nucleus and cytosol, affecting photosynthesis, translation, transcription, and splicing. Virus infection is a process resulting in numerous molecular, cellular, and physiological changes, a wide range of which can be analyzed due to development of many high-throughput techniques. Plant RNA viruses are known to replicate in the cytoplasm; however, the roles of chloroplasts and other cellular structures in the viral replication cycle and in plant antiviral defense have been recently emphasized. Therefore, the aim of this study was to analyze the small RNAs, transcripts, proteins, and phosphoproteins affected during peanut stunt virus strain P (PSV-P)–Nicotiana benthamiana interactions with or without satellite RNA (satRNA) in the context of their cellular localization or functional connections with particular cellular compartments to elucidate the compartments most affected during pathogenesis at the early stages of infection. Moreover, the processes associated with particular cell compartments were determined. The ‘omic’ results were subjected to comparative data analyses. Transcriptomic and small RNA (sRNA)–seq data were obtained to provide new insights into PSV-P–satRNA–plant interactions, whereas previously obtained proteomic and phosphoproteomic data were used to broaden the analysis to terms associated with cellular compartments affected by virus infection. Based on the collected results, infection with PSV-P contributed to changes in the abundance of transcripts and proteins associated with various cellular compartments, including ribosomes, chloroplasts, mitochondria, the nucleus and the cytosol, and the most affected processes were photosynthesis, translation, transcription, and mRNA splicing. Furthermore, sRNA-seq and phosphoproteomic analyses indicated that kinase regulation resulted in decreases in phosphorylation levels. The kinases were associated with the membrane, cytoplasm, and nucleus components.