Proteins cell synthesis

Product formation kinetics in mammalian cells has been studied extensively for hybridomas. Most monoclonal antibodies are produced at an enhanced rate during the Gq phase of the cell cycle (8—10). A model for antibody production based on this cell cycle dependence and traditional Monod kinetics for cell growth has been proposed (11). However, it is not clear if this cell cycle dependence carries over to recombinant CHO cells. In fact it has been reported that dihydrofolate reductase, the gene for which is co-amplified with the gene for the recombinant protein in CHO cells, synthesis is associated with the S phase of the cell cycle (12). Hence it is possible that the product formation kinetics in recombinant CHO cells is different from that of hybridomas. 

Navab, M., Imes, S.S., Hama, S.Y., Hough, G.P., Ross, L.A., Bork, R.W., Valente, A.J., Berliner, J.A., Drinkwater, D.C., Laks, H. and Fogelman, A.M. (1991). Monocyte transmigration induced by modification of low density lipoprotein in cocultures of human aortic endothelial cells is due to induction of monocyte chemotactic protein 1 synthesis and is abolished by high density lipoprotein. J. Clin. Invest. 88, 2039-2046. 

MHC antigens and P2-macroglobulin are amongst the best known proteins whose synthesis is also induced in a variety of cell types in response to various interferons. 

Strick R, Laemmli UK (1995) SARs are cis DNA elements of chromosome dynamics synthesis of a SAR repressor protein. Cell 83(7) 1137-1148... 

Figure 9.17 Green fluorescent protein (GFP) synthesis in water-in-oil emulsion as visualized by fluorescence microscopy. (Adapted from Pietrini and Luisi, 2004). Shown are the compartments in which GFP has been expressed (green in the original), (a) Typical micrographs of the cell-free GFP synthesis in Span 80 (0.45% v/v)/Tween 80 (0.05% v/v)/aqueous solution (0.5% v/v) in mineral oil emulsion droplets, preparation at 4 °C incubation at 37°C (i) 0 min, (ii) 11 min, (iii) 23 min, (iv) 32 min, (v) 44 min, (vi) 57 min, (vii) 21 h. Negative control (viii) 0 min, (ix) 21 h. The bar represents 50 p.m. (b) Kinetics of the cell-free GFP synthesis in emulsion droplets, on average 10 droplets with diameters of 30-60 um are evaluated per time point, cell-free enhanced GFP synthesis in emulsion droplets (i, ii and iii are three independent experiments) and negative controi (iv and v are two independent experiments).

Schachtschabel, D. and Zillig, W. (1959) Investigations on the biosynthesis of proteins. I. Synthesis of radiocarbon labeled amino acids in proteins of cell-free nucleoprotein-enzyme-system of Escherichia coli. Hoppe-Seyler s Z. Physiol. Chem. 314, 262-275. 

Z3. Zoja, C., Morigi, M., Figliuzzi, M., Bruzzi, I., Oldroyd, S., Benigni, A., Ronco, P., and Remuzzi, G., Proximal tubular cell synthesis and secretion of endothelin-1 on challenge with albumin and other proteins. Am. J. Kidney Dis. 26, 934-941 (1995). 

RNA) A biopolymer of ribonucleotides that controls the synthesis of proteins. The synthesis of RNA is generally controlled by and patterned after DNA in the cell. (p. 1143)... 

Giriat 1, Muir TW. Protein semi-synthesis in living cells. J. Am. Chem. Soc. 2003 125(24) 7180-7181. 

The flow of genetic information in normal cells is from DNA to RNA to protein. The synthesis of RNA from a DNA template is called transcription, whereas the synthesis of a protein from an RNA template is termed translation. Cells contain several kinds of RNA messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA), which vary in size from 75 to more than 5000 nucleotides. All cellular RNA is synthesized by RNA polymerase according to instructions given by DNA templates. The activated intermediates are ribonucleoside triphosphates and the direction of... 

Translesion synthesis with DNA Pol of the A-acetyl-2-aminofluorene adduct of guanosine (88) is inefficient with templates containing (88). In the presence of the Revl protein, translesion synthesis occurs and dCTP is the major nucleotide incorporated opposite it, and studies with a mutant DNA Pol I gave similar results. Benzo[a]pyrene is a potent environmental carcinogen, which when metabolised leads to u t -benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide anti-BPDE). With dG, the major lesion is (+)-tra w-a h-B[a]P-A -dG, (89), and is usually repaired by the nucleotide excision repair (NER) pathway. The translesion synthesis past (89) has been examined with a number of polymerases. With human RNA Pol II, (89) is a block to synthesis, whilst DNA Pol k preferentially incorporated the correct nucleotide. In yeast cells, Pol induced a large number of mutations involving Pol p, whilst Pol p alone contributed to 1-3 deletions or insertions. The NER of (89) with UvrB proteins was also studied. ... 

The plasma membrane of the cell is a lipid bilayer sheet in which membrane-bound proteins are embedded. Steps 4B-6B of Figure 1.21 illustrate some events in the production of a membrane-bound protein. After synthesis of the protein, the ribosome on which it was formed dissociates from the membrane but the protein remains bound to the membrane (Step 4B). This binding is mediated by a short stretch of lipophilic amino acids that may occur near the C terminus, as shown in Figure 1.21, or near the N terminus in the case of other proteins. Subsequently, part of the ER membrane forms a bud that breaks off (Step 5B) to form a secretory vesicle (Step 6B). The continued association of the entire membrane-bound protein during the budding process and during subsequent events is maintained by the special lipophilic sequence. Eventually, the secretory vesicle fuses with the plasma membrane in a process that resembles a reversal of Steps 4B-6B. After completion of the insertion of the membrane-bound protein into the plasma membrane, its N terminus is in contact with the extracellular fluid and its C terminus is in contact with the cytoplasm, at least for the protein depicted in Figure 1.21. 

Albumin is synthesized primarily by the hepatic parenchymal cells except in early fetal life, when it is synthesized largely by the yolk sac. The synthetic reserve of the liver is enormous in nephrotic syndrome, it may be 300% or more of normal. The synthetic rate is controlled primarily by colloidal osmotic pressure (COP) and secondarily by protein intake. Synthesis is decreased by inflammatory cytokines, and release (but not synthesis) is decreased by hypokalemia. Catabolism occurs primarily by pinocytosis by aU tissue, with lysosomal catabolism of the protein and use of the resulting free amino acids for synthesis of cellular proteins. The rate of pinocytosis is proportional to the local tissue metaboHc rate. Small amounts (10% to 20% of the total catabolized) are also lost into the gastrointestinal tract... 

PTH also increases intestinal calcium absorption by increasing 1,25 (OH) 2D. PTH is a major trophic factor for renal 25(OH)t>-la-hydroxylase. It increases the conversion of 25(0H)D to the active vitamin D metabolite, l,25(OH)2D. Calcium is absorbed principally in the duodenum, although it can also be absorbed by the distal small bowel and colon. About 30% of a daily calcium intake of 1 g (25 mmo ) is absorbed. Approximately 100 mg (2.5 mmol) of calcium is secreted into gut lumen by intestinal secretion therefore net calcium absorption is 200 mg (5.0 mmol)/day. Calcium is absorbed by passive diffusion and by an active transport system. It is estimated that passive diffusion accounts for absorption of about 10% of ingested calcium per day. Active calcium absorption in the duodenum is under the control of l,25(OH)2D. This vitamin D metabolite increases the intestinal cell synthesis of a calcium-binding protein (CaBP), which enhances the net absorption of ingested calcium. 

---