Intracellular cytoplasm

Figure 18.1 Typical tangle (T) and plaque (P) as visualised by silver impregnation in the cerebral cortex of a case of Alzheimer s disease. The extracellular plaque (10-50 pm diameter) consists of a central core of amyloid surrounded by glial processes and a number of neurites in a ring formation. The intracellular cytoplasmic tangle is composed of helical filaments in a paired format. (Reproduced with permission of Academic Press from Wischik and Crowther 1986)...

CCR3 gene missense polymorphisms, including the Arg275Glu substitution in the third extraceUnlar loop and the Len302Pro substitution in the intracellular cytoplasmic tail, have been identified. As yet, however, no phenotype has been associated with these polymorphisms (228). 

Mechanism of Action A cardiac inotropic agent that increases the influx of calcium from extracellular to intracellular cytoplasm. Therapeutic Effect Potentiates the activity of the contractile cardiac muscle fibers and increases the force of myocardial contraction. Slows the heart rate by decreasing conduction through the SA and AV nodes. Pharmacokinetics ... 

H. Bach, Y. Mazor, S. Shaky, A. Shoham-Lev, Y. Berdichevsky, D. L. Gutnick, and I. Benhar, Escherichia coli maltose-binding protein as a molecular chaperone for recombinant intracellular cytoplasmic single-chain antibodies,/. Mol. Biol. 2001, 312, 79-93. 

The G protein complexes related to thyrotrophs TRH receptors affect phosphoinositide-specific phospholipase C, which increases intracellular cytoplasmic free calcium, thereby stimulating TSH secretion. 

Despite this complexity, most integrins share two, key interrelated functions first, to promote the assembly and organization of the actin cytoskeleton [122, 123] and second, to regulate signal transduction cascades [124-126], Spanning the cell membrane, these subunits serve as a communication pathway, linking the actin cytoskeleton and intracellular cytoplasmic proteins involved in focal adhesion complexes (FACs) with the cell s dynamic extracellular environment (Fig. 8) [127-130]. There are at least 50 distinct proteins known to be involved in FACs. Actin [131], vinculin, talin, tensin, a-actinin, and filamin provide a structural role, while focal adhesion kinase [132], integrin-linked kinase, Src-family kinase, PINCH, paxillin... 

Gap junctions (nexus) are broad areas of closely opposed plasma membranes, but there is no fusion of the plasma membranes and a narrow gap, of about 2 to 3 nm wide, remains. The gap is crossed by cytoplasmic filaments, which allow intracellular cytoplasm to transfer between cells. This type of cell junction not only functions as an adherent zone, but also permits the passage of ions and other small molecules (sugars, amino acids, nucleotides and vitamins). Thus the gap junctions are sites of intercellular information exchange. 

Mechanism of action Spironolactone [spye row no LAK tone] is a synthetic aldosterone antagonist that competes with aldosterone for intracellular cytoplasmic receptor sites. The spironolactone-receptor complex is inactive, that is, it prevents translocation of the receptor complex into the nucleus of the target cell, and thus does not bind to DNA. This results in a failure to produce proteins that are normally synthesized in response to aldosterone. These mediator proteins normally stimulate the Na+-K+ exchange sites of the collecting tubule. Thus, a lack of mediator proteins prevents Na+ reabsorption and therefore K+ and H+ secretion. 

The adrenocorticoids bind to specific intracellular cytoplasmic receptors in target tissues. The receptor-hormone complex then translocates into the nucleus where it acts as a transcription factor to turn genes on or off, depending on the tissue. This mechanism requires time to produce an effect. There are other glucocorticoid effects, such as their requirement for catecholamine-mediated dilation of vascular and bronchial musculature or lipolysis, whose effects are immediate. The bases for these actions are unknown. 

In this context we will use the broad definition of protein aggregate referring to all aggregations of misfolded and accumulated ubiquitinated protein no matter whether extra-or intracellular, cytoplasmic or nuclear and whether or not associated with microtubuli. 

The /3-D-glucosidases studied were intracellular (cytoplasmic) enzymes of high molecular weight, about 300,000 (see Table XII), but... 

The first demonstration of intracellular receptors was the finding of target tissues in the uterus (Jensen and Jacobson, 1960). A generalized steroid-receptor hypothesis has evolved since then in which the putative intracellular cytoplasmic protein is activated. The specific steroid enters the cell as a free compound, but arrives at its target in a mostly protein-bound form. Following activation the complete steroid-receptor complex is translocated to the... 

Fig. 4.8. Major classes of drug receptors. (A) Transmembrane ligand-gated ion channel receptor. (B) Transmembrane G protein-coupled receptor (GPCR). (C) Transmembrane catalytic receptor or enzyme-coupled receptors. (D) Intracellular cytoplasmic/nuclear receptor. (From Simon JB, Golan DE, Tashjian A, Armstrong E, et al., eds. Chapter 1, Drug-Receptor Interactions. In Principles of Pharmacology The Pathophysiologic Basis of Drug Therapy. Baltimore Lippincott Williams Wilkins, 2004, pp. 3-16, with permission.)...

Intracellular (cytoplasm and/or nucleus) Steroids and thyroid hormones Modification of RNA-directed protein synthesis and the transcriptional activity of responsive genes... 

CC chemokine activities are mediated by seven-transmembrane domain, Gprotein-coupled receptors (see Chap. 2). The CC chemokine receptors are structurally homologous. While the transmembrane and the second and third intracellular/ cytoplasmic domains of these receptors are well conserved, the NH2- and COOH-... 

It has been suggested that the induction of oocyte maturation with steroids is a two-step process (Smith and Ecker, 1970b, 1971 also Masui, 1972). First steroids interact with a component at or near the oocyte surface, and this leads to appearance of a second intracellular (cytoplasmic ) component which somehow results in other maturational events. In general form, this hypothesis is similar to those proposed for polypeptide hormones (review by Robinson et al., 1971) and steroids (Jensen et al., 1969 Gorski et al., 1969), as well as for the induction of maturation in starfish oocytes with 1-methyladenine (review by Kanatani, 1972). 

Peroxisomes are intracellular cytoplasmic organelles and the major sites for enzymatic oxidation, including that of fatty acids. The proliferation of peroxisomes is stimulated by free fatty acids and some metabolites of arachidonic acid, which are ligands for nuclear receptor proteins, the PPARs. These, in turn, are a family of... 

SOD is a selective scavenger of 02, is abundandy found in the intracellular cytoplasmic space of aerobic organisms, and plays a central role in protecting cells from 02 -induced oxidative stress. It protects the organism against the toxic effects of the... 

The intracellular cytoplasmic concentration of calcium is under the influence of several ion pumps. One exists at the level of the mitochondrial membrane, which actively transports Ca + into the mitochondrial matrix. Release of calcium from the mitochondria occurs by passive diffusion. A second pump exists in many cells in the endoplasmic reticulum. Here, at the expense of ATP, calcium is brought into the ER cister-... 

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