Cytoplasm defined

The refractive index of erythrocyte cytoplasm, defined by the cell bounded haemoglobin solution, can be found from the following equation [8, 84] ... 

About 70% of the ribosomes in Chlamydomonas are cytoplasmic (defined here as extraorganellar). These are about 82 S and are composed of 61 S and 41 S subunits. These two subunits contain RNAs of 1.3 x 10 and 0.69 X 10 daltons plus 39 and 26 proteins, respectively. Almost all the remaining ribosomes are in the chloroplast. These sediment at about 68 S, are composed of a 52 S and a 37 S subunit, contain rRNAs of 1.09 x 10 and 0.55 x 10 daltons, respectively, and are constituted of 26 and 22 proteins, respectively. Figure 10 shows the separation of the four C. rein-hardi ribosomal subunits Figure 11 shows the rRNAs obtained from the subunits Figures 12 and 13 are two-dimensional polyacrylamide gel maps of the ribosomal proteins. 

Catenins are defined as cytoplasmic interaction partners of cadherins that form a chain of proteins ( catena, latin for chain), which connects cadherins to the actin cytoskeleton. 

The eukaryotic somatic cell cycle is defined by a sequential order of tasks a dividing cell has to complete it must replicate its DNA, segregate its chromosomes, grow, and divide. The cell cycle can be divided into four discrete phases. DNA replication is restricted to S phase (DNA synthesis phase), which is preceded by a gap phase called G1 and followed by a gap phase called G2. During mitosis (M phase) the sister chromatids are segregated into two new daughter nuclei and mitosis is completed by the division of the cytoplasm termed cytokinesis (Fig. 1). 

In addition to the membrane-inserted core domain of Kv channels, their cytoplasmic domains have important roles for Kv-channel function [5]. Many of these functions are related to subunits assembly, channel trafficking to and from the plasma membrane, and interactions with cytoskeletal components (Fig. la). A tetramerization (T) domain for subunit assembly has been well defined in Shaker-channels, where it is localized in the amino-terminus. Other Kv-channels (e.g., eag, HERG, KvLQTl) may have comparable domains within the cytoplasmic carboxy-terminus. ER retention and retrieval signals have been found... 

A three-dimensional meshwork of proteinaceous filaments of various sizes fills the space between the organelles of all eukaryotic cell types. This material is known collectively as the cytoskeleton, but despite the static property implied by this name, the cytoskeleton is plastic and dynamic. Not only must the cytoplasm move and modify its shape when a cell changes its position or shape, but the cytoskeleton itself causes these movements. In addition to motility, the cytoskeleton plays a role in metabolism. Several glycolytic enzymes are known to be associated with actin filaments, possibly to concentrate substrate and enzymes locally. Many mRNA species appear to be bound by filaments, especially in egg cells where they may be immobilized in distinct regions thereby becoming concentrated in defined tissues upon subsequent cell divisions. 

NF-xB, originally defined as the enhancer of kappa light-chain expression in B lymphocytes, is a hcterodimeric protein that can rapidly activate several genes associated with the inflammatory process (reviewed by Schreck et al., 1992). The DNA binding, nuclear form, of NF-xB is a heterodimer composed of one Rel-A (65 kD) and one p50 (50 kD) subunit. However, both subunits can form homodimers that also have DNA-binding activity. The inactive form of NF-xB in non-stimulated cells is localized to the cytoplasm of resting cells, and is bound to its inhibitor IxB. 

The distribution of elements in single-cell non-photosynthetic eukaryotes is probably best seen in terms of the well-defined compartments of yeast. The central cytoplasmic compartment containing the nucleus has many free element concentrations, only somewhat different from those in all known aerobic prokaryotes (Figure 7.7). (The nuclear membrane is a poor barrier to small molecules and ions and so we include the nucleus with the cytoplasm.) We do not believe in fact that the free cytoplasmic values of Mg2+, Mn2+, Fe2+, Ca2+, and possibly Zn2+, have changed greatly throughout evolution. As stressed already there are limitations since free Mg2+ and Fe2+ are essential for the maintenance of the primary synthetic routes of all cells, and changes in other free metal ions could well have imposed... 

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