Cellular functions cells

E. Scotti, F. Gilardo, C. Godio, E. Gers, J. Krneta, N. Mitro, E. De Fabiano, D. Caruso and M. Crestani, Bile acids and their signalling pathways eclectic regulators of diverse cellular functions. Cell Mol. Life Sci., 2007, 64, 2477-2491. 

The cytoskeletal network is responsible for the mechanical properties of the cell that modulate functions such as cell shape, locomotion, cytokinesis, and translocation of organelles. Experimental evidence suggests that the cytoskeleton also provides connections between cellular structures and presents a large surface area for interactions of various proteins and signaling molecules. Modulation of the cytoskeletal network may influence cell signaling, ion channels and intracellular calcium levels. Cytoskeleton is thus essential for regulation of cellular functions, cell integrity, and viability. 

Olzscha H, Schermann SM, Woemer AC, Pinkert S, Flecht MH, Tartaglia GG, Vendruscolo M, Hayer-Flartl M, Hartl FU, Vabulas RM (2011) Amyloid-like aggregates sequester numerous metastable proteins with essential cellular functions. Cell 144 67-78... 

F.J. Doyle, J. Doyle, Robustness of cellular functions, Cell 2004, 118, 675-685. 

RNAs are generally classified according to their cellular functions. Cells contain three major classes of RNA, which participate in protein biosynthesis. They are transfer RNA or soluble RNA (tRNA or sRNA), ribosomal RNA (rRNA) and messenger RNA... 

As stated above, calcium is an extremely important cellular ion for several cellular functions. The concentration of calcium in human extracellular fluid is about 2.5 mM, while the intracellular concentration is only 100-200 nM depending on the cell type. Thus, there is 10 000-20 000 fold concentration difference between the cell interior and exterior that has to be maintained by cellular pumping mechanisms. This requires a large amount of energy. " ... 

The nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are the chemical carriers of a cell s genetic information. Coded in a cell s DNA is the information that determines the nature of the cell, controls the cell s growth and division, and directs biosynthesis of the enzymes and other proteins required for cellular functions. 

The primary cellular function of mRNA is to direct biosynthesis of the thousands of diverse peptides and proteins required by an organism—perhaps 100,000 in a human. The mechanics of protein biosynthesis take place on ribosomes, small granular particles in the cytoplasm of a cell that consist of about 60% ribosomal RNA and 40% protein. 

The ankyrin repeat motif is one of the most common protein-protein interaction domains. Ankyrin repeats are modules of about 33 amino acids repeated in tandem. They are found in a large number of proteins with diverse cellular functions such as transcriptional regulators, signal transducers, cell-cycle regulators, and cytoskeletal proteins. 

Ca2+ is an important intracellular second messenger that controls cellular functions including muscle contraction in smooth and cardiac muscle. Ca2+ channel blockers inhibit depolarization-induced Ca2+ entry into muscle cells in the cardiovascular system causing a decrease in blood pressure, decreased cardiac contractility, and antiarrhythmic effects. Therefore, these drugs are used clinically to treat hypertension, myocardial ischemia, and cardiac arrhythmias. 

Cyclic nucleotides (cAMP and cGMP) are formed enzymatically from the corresponding triphosphates. As ubiquitous second messengers, they mediate many cellular functions which are initiated by first (extracellular) messengers. Their prime targets in eucaryotic cells are protein kinases ( cyclic AMP-dependent protein kinase, cyclic GMP-dependent protein kinase), ion channels and ensymes. 

A process in which a substance gains entry into a cell. Endocytic mechanisms are crucial for a variety of cellular functions such as the uptake of nutrients, regulation of cell surface expression of receptors, maintenance of cell polarity, and more. Receptor-mediated endocytosis via clathrin-coated pits is the most studied endocytic process, which is important for regulation of the time and magnitude of signals generated by a variety of cell-surface receptors. 

Other, more general effects of insulin on cellular function include stimulation of cell growth (increase in DNA and protein synthesis), inhibition of apoptosis, and modulation of ion-channel activity. 

PKC isozymes are involved in a wide array of diverse cellular functions [5]. Most isozymes (e.g., PKC (3) are involved in proliferative responses, and hyperactivation with phorbol esters most typically results in cell growth and differentiation. However, isozymes can have opposing functions. PKC 8 is well-characterized as an apoptotic kinase, whereas the closely related PKC e is antiapoptotic. PKC also plays a key role in learning and memory. 

Proteosomal degration is the process by which improperly folded proteins or proteins with altered post-translational modifications are removed from a cell before they have a detrimental effect on cellular function. This is performed in small organelles known as proteosomes. Proteins are targeted for destruction in the proteosome by having a number of small ubiquitin molecules added. 

Thomas SM, Brugge JS (1997) Cellular functions regulated by Src family kinases. Annu Rev Cell Dev Biol 13 513-609... 

In concordance with the central role of ubiquitin modification in multiple cellular functions perturbations of this system are associated with a variety of diseases. Defects in the control of cell cycle regulators by the ubiquitin proteasome system are connected to cancer progression and many E3 ligases were originally identified as oncogenes. 

Most drag s act on the body by altering cellular function. A drug cannot completely change the function of a cell, but it can alter its function. A drug that alters cellular function can increase or decrease certain physiologic functions, such as increase heart rate, decrease blood pressure, or increase urine output. 

Microtubules are universally present in eukaryotes from protozoa to the cells of higher animals and plants (Porter, 1966 Hardham and Gunning, 1978 Lloyd, 1987), but they are absent in mammalian erythrocytes and in prokaryotes. Microtubules participate in a number of cellular functions including the maintenance of cell shape and polarity, mitosis, cytokinesis, the positioning of organelles, intracellular transport to specific domains, axoplasmic transport, and cell locomotion. The diversity of microtubule fimctions suggests that not all microtubules are identical and that different classes of microtubules are present in different cell types or are localized in distinct domains in the same cell type (Ginzburg et al., 1989). 

Holzbaur, E.L.F. Vallee, R.B. (1994). Dyneins Molecular structure and cellular function. Ann. Rev. Cell Biol. 10,339-372. 

Tiwari, S.C., Wick, S.M., Williamson, R.E., Gunning, B.E. (1984). Cytoskeleton and integration of cellular function in cells of higher plants. J. Cell Biol. 99,63S-69S. 

For most tissues, cells and organs, the effects of cold on the cellular membrane are fully reversible. Cells cooled to 1 °C to 4 °C for short periods of time (about four hours) can regain normal cellular functions, including membrane-linked functions, when rewarmed. This seems to suggest that the phase transition in the membrane-bound phospholipids is reversible when the temperature is elevated to normothermia. 

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