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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.
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TL;DR: This chapter discusses the mechanisms and functional role of glycosylation in membrane protein synthesis and the synthesis of asparagine-linked glycoproteins involves a complex series of reactions catalyzed by soluble and membrane-associated enzymes in at least three cellular compartments.
Abstract: Publisher Summary This chapter discusses the mechanisms and functional role of glycosylation in membrane protein synthesis. The lipid moiety of the glycosylation intermediates in bacterial glycan synthesis is known to be a phosphorylated polyisoprenol lipid (undecaprenyl phosphate). As dolichol—a family of lipids characterized by having 16–22 isoprene units with the α-isoprene unit saturated—is the abundant polyisoprenol lipid in mammalian tissues, even the earliest report of glycosylation intermediates in mammalian tissues implicated dolichyl phosphate as the lipid carrier. There are three general approaches used to determine the role of protein-bound carbohydrate. First, the properties of glycosylated and nonglycosylated forms of an isolated protein are examined. Second, the function and compartmentalization of a protein in an untreated cell can be compared to that in a cell treated with an inhibitor of glycosylation. Then, the function of a glycoprotein in a normal cell can be compared with that in a mutant cell defective in glycosylation. The synthesis of asparagine-linked glycoproteins involves a complex series of reactions catalyzed by soluble and membrane-associated enzymes in at least three cellular compartments. Dolichyl phosphate is clearly involved in glycosylation; it remains to be determined whether other polyisoprenoids are as well.
23 citations
TL;DR: The localization of heat shock messages in the processes of these neural cell types could provide a mechanism for local control of synthesis of heatshock proteins in cellular compartments that are remote from the cell body.
Abstract: Heat shock proteins are essential cellular proteins that may play important roles in cellular repair and/or protection. This report focuses on the expression of two members of the hsp70 multigene family, namely, constitutive hsc70 mRNA and stress-inducible hsp70 mRNA in the control and hyperthermic rabbit brain. The intracellular localization of these heat shock mRNAs was examined using high-resolution nonradioactive in situ hybridization. The distribution of hsc70 mRNA and hsp70 mRNA was examined in (1) neuronal cell bodies and their dendritic processes and (2) oligodendrocytes and their cellular processes. In control animals, hsc70 mRNA was detected in the apical dendritic processes and cell bodies of cortical layer II and V neurons, CA3 and CA4 neurons, deep cerebellar neurons, and brainstem neurons. A time course analysis of hsc70 mRNA, after a physiologically relevant increase in body temperature of 2.6 degrees C, revealed more distal transport of this constitutive message into dendrites of these neuronal populations. In the same neuronal populations, basal levels of hsp70 mRNA were observed in the cell body; however, this mRNA was not detected in dendritic processes in control or hyperthermic animals. After hyperthermia, hsp70 mRNA was strongly induced in oligodendrocytes and transported to the processes of these glial cells. The localization of heat shock messages in the processes of these neural cell types could provide a mechanism for local control of synthesis of heat shock proteins in cellular compartments that are remote from the cell body.
23 citations
TL;DR: This work proposes that membrane perturbation may serve as an alternative mechanism to activate a conserved cell-death program in cancer cells, and suggests that HAMLET-induced curvature-dependent membrane conformations serve as surrogate receptors for initiating signal transduction cascades, ultimately leading to cell death.
Abstract: A central tenet of signal transduction in eukaryotic cells is that extra-cellular ligands activate specific cell surface receptors, which orchestrate downstream responses. This ''protein-centric" view is increasingly challenged by evidence for the involvement of specialized membrane domains in signal transduction. Here, we propose that membrane perturbation may serve as an alternative mechanism to activate a conserved cell-death program in cancer cells. This view emerges from the extraordinary manner in which HAMLET (Human Alpha-lactalbumin Made LEthal to Tumor cells) kills a wide range of tumor cells in vitro and demonstrates therapeutic efficacy and selectivity in cancer models and clinical studies. We identify a ''receptor independent" transformation of vesicular motifs in model membranes, which is paralleled by gross remodeling of tumor cell membranes. Furthermore, we find that HAMLET accumulates within these de novo membrane conformations and define membrane blebs as cellular compartments for direct interactions of HAMLET with essential target proteins such as the Ras family of GTPases. Finally, we demonstrate lower sensitivity of healthy cell membranes to HAMLET challenge. These features suggest that HAMLET-induced curvature-dependent membrane conformations serve as surrogate receptors for initiating signal transduction cascades, ultimately leading to cell death.
23 citations
TL;DR: Physical evidence for MCSs between two membranes is presented and it is proposed for the ER-chloroplast pair, that such tight associations are involved in bidirectional lipid trafficking between the two compartments.
23 citations
TL;DR: Microanalysis studies performed on quickly frozen, freeze substituted and embedded eggs showed a transient Ca2+ enrichment of mitochondria soon after fertilization thus suggesting that mitochondria behave as a Ca2- sink at fertilization.
23 citations