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.

Nucleus and Cytoplasm: Supply and Demand

Abstract: The main problem to be discussed in this chapter pertains to the interrelationship of the nucleus and the cytoplasm in the control of gene expression in eukaryotes. The presence of the nuclear envelope in eukaryotic cells results in the separation of transcription from translation in space and time. Hence, a number of questions arise as to the role of each of the cellular compartments in protein synthesis. For example, does the nucleus itself have total control over this process, with the cytoplasm acting merely to execute the orders issued from the nucleus? In other words, is the nuclear “supply” (via regulation at the transcriptional level) sufficient to specify qualitatively the spectrum of proteins to be synthesized in the cell and to regulate their rates of synthesis, or does cytoplasmic “demand” for certain messengers also play a role in this process?

Phosphorylation/dephosphorylation mechanisms in coated vesicles.

Abstract: Publisher Summary A major development in cell biology in the past few years has been the gradual realization of the magnitude of intracellular membrane traffic and the multiplicity of pathways for such traffic in various cells. These intracellular transfers of membranous proteins among discontinuous regions of membrane occur via the populations of vesicles. The chapter focuses on the specialized vesicular structures, the coated vesicles (CV), in relation to this intracellular traffic. The transfer of membranes and associated components among cellular compartments involves the vesiculation of one membrane bilayer and further fusion of the vesicle with another one. CV are widely involved in the first of these steps. The formation of a lattice-like coat from clathrin and associated proteins accompanies vesiculation. Clathrin-coated vesicles have been found to be involved in the transport of membranes and/or proteins along major established pathways. The kinase/phosphatase system associated to its specific pp50 substrate constitutes an extraordinary useful tool to study fundamental biochemical problems, such as protein–protein interactions, enzymatic regulation, and the molecular and physiological significance of protein phosphorylation. The different localization of the two antagonistic enzymatic activities amid the CV structure seems to indicate that pp50 plays an interface role between the membranous vesicle core and the clathrin coat.

Complexity of Stress Signaling

Abstract: Publisher Summary This chapter emphasizes the key stress signals in various cellular compartments and focuses on current knowledge of the sensing mechanisms. The mitochondria are a crucial center for stress detection and processing of stress signals arising in other cellular compartments. Mitochondria activate apoptosis in response to external signals or stresses detected within the mitochondrion. The p53 in the cytosol can localize to the mitochondria and instigate apoptosis. Metabolic and other stresses, such as ionizing and some types of ultraviolet (UV) radiation may increase the mitochondrial reactive nitrogen species (ROS) production rate beyond the detoxification capacity. Elevated metabolic activity increases electron leakage from complex I and subsequent ROS production. The ER is where secretory proteins are processed, a variety of posttranslational modifications are made, and it is the site of intracellular Ca 2+ storage. Stresses affecting Ca 2+ levels or the redox balance are the most notable ER stress signals that impact protein folding. Ca 2+ is essential for a number of enzymes, including some involved in protein processing. Signal transduction can occur through precise protein to protein relays, or through less specific mechanisms where the concentration of a molecule is changed and sensors respond to the change in concentration gradient. The archetypical protein based method for conveying a highly specific signal is through phosphorelays where proteins pass a phosphate through a transduction pathway. Protein modification is a major mechanism for stress signal propagation within the cell and other methods that proteins use for passing messages includes acetylation, ISGylation, nitrosylation, ROS generation, and sumolyation.

FRET Flow Cytometry-Based High Throughput Screening Assay To Identify Disrupters of Glucose Levels in Trypanosoma brucei

Abstract: Trypanosoma brucei, which causes human African typanosomiasis (HAT), derives cellular ATP from glucose metabolism while in the mammalian host. Targeting glucose uptake or regulation in the parasite has been proposed as a potential therapeutic strategy. However, few methods have been described to identify and characterize potential inhibitors of glucose uptake and regulation. Here, we report development of a screening assay that identifies small molecule disrupters of glucose levels in the cytosol and glycosomes. Using an endogenously expressed fluorescent protein glucose sensor expressed in cytosol or glycosomes, we monitored intracellular glucose depletion in the different cellular compartments. Two glucose level disrupters were identified, one of which only exhibited inhibition of glycosomal glucose and did not affect cytosolic levels. In addition to inhibiting glucose uptake with relatively high potency (EC50 = 700 nM), the compound also showed modest bloodstream form parasite killing activity. Expandi...