Membranes, cell nuclear

Nucleus The nucleus is separated from the cytosol by a double membrane, the nuclear envelope. The DNA is complexed with basic proteins (histones) to form chromatin fibers, the material from which chromosomes are made. A distinct RNA-rich region, the nucleolus, is the site of ribosome assembly. The nucleus is the repository of genetic information encoded in DNA and organized into chromosomes. During mitosis, the chromosomes are replicated and transmitted to the daughter cells. The genetic information of DNA is transcribed into RNA in the nucleus and passes into the cytosol where it is translated into protein by ribosomes. 

CNTs as therapeutic or diagnostic agents need to penetrate in vivo barriers including the tissue endothelium, cell membranes, perinuclear membranes, and nuclear... 

Cell wall Cell membrane Ribosome Nuclear region Cytoplasm... 

Farach-Carson MC, Davis PJ. Steroid hormone interactions with target cells cross talk between membrane and nuclear pathways. J Pharmacol Exp Ther. 2003 307 839-845. 

The mineralized matrix of bone tissue is strained when loaded. Macro-molecular mechanical connections between the extracellular matrix and the osteocytic cell membrane exist and these connections may be capable of transmitting information from the strained extracellular matrix to the bone cell nuclear membrane. The basis of this mechanism is the physical continuity of the transmembrane integrin molecule, which is connected extracellularly with the macromolecular collagen of the organic matrix and intracellularly with the... 

R8. Rekvig, O. P., and Hannestad, K., The specificity of human autoantibodies that react with both cell nuclei and plasma membranes The nuclear antigen is present on core mononucleosomes. J. Immunol. 123, 2673-2681 (1979). 

Cytochrome P-450 reductase (present in cell nuclear membranes) catalyzes reduction of the anthracyclines to semiquinone free radicals. These in turn reduce molecular 02, producing superoxide ions and hydrogen peroxide that mediate single strand scission of DNA (Figure 38.10). Tissues with ample superoxide dismutase (SOD) or glutathione peroxidase activity are protected.6 Tumors and the heart are generally low in SOD. In addition, cardiac tissue lacks catalase and thus cannot dispose of hydrogen peroxide. This may explain the cardiotoxicity of anthracyclines. 

Changes in Plasma Membrane and Nuclear Proteins in MCF-7 Cells Resistant to Mitoxantrone 253... 

An important question is how to achieve the most efficient delivery of PNA. This problem does not usually have a definite answer and many different factors must be considered. Table 1 reviews the main types of PNA-peptide conjugates and indicates the most important issues in each case. The internalization routes are schematically drawn in Fig. 2. Depending on the peptide attached, the PNA oligomer is internalized via endocytosis or directly delivered across the cell membrane. For nuclear localization signals (NLS) and tetralysine (K4) the delivery route is not clear yet. The same holds true for nuclear delivery with CPPs. Some CPPs (e.g., transportan) have been shown to accumulate in the nucleus, while others have not. 

Nuclear Membrane The nuclear membrane separates the nucleus and the nucleolus from the rest of the contents of the cell. 

In more complex viruses, the nucleocapsid is surrounded by a membrane envelope, which usually arises from the host cell nuclear or plasma membranes. Envelope proteins, coded for by the viral genome, are inserted into the envelope membrane during virion assembly. Proteins that protrude from the surface of the envelope, called spikes, are believed to mediate the attachment of the virus to the host cell. Representative viruses are illustrated in Figure 17.24. 

Cell Wall Cell. Membrane Cytoplasm Cell Nuclear region Ribosome... 

Lithgow, T., van, D.R., Bertram, J.F., and Strasser, A. (1994). The protein product of the oncogene bcl-2 is a component of the nuclear envelope, the endoplasmic reticulum, and the outer mitochondrial membrane. Cell Growth Differ. 5, 411-417. 

A variety of processing events follow protein synthesis. In eukaryotes, many of these modifications are associated with specific subcellular compartments. For example, glycosylation of proteins requires enzymes that are present both in the endoplasmic reticulum and the Golgi apparatus. Other proteins need to be localized to specific regions in the cell, for example, the localization of integral membrane proteins to the plasma membrane, or nuclear -encoded mitochondrial proteins that are synthesized in the cytosol but need to be imported into the mitochondria. 

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