Replication activator protein

How is replication tied to cell division Replication is tied to cell division by several proteins including the origin recognition complex, replication activator protein, and rep-hcation licensing factors. The process is controlled by cyclins, proteins produced during the Gj and S phases that bind to cyclin-dependent kinases and activate replication. 

Alternatively, one interesting drug delivery technique exploits the active transport of certain naturally-occurring and relatively small biomacromolecules across the cellular membrane. For instance, the nuclear transcription activator protein (Tat) from HIV type 1 (HlV-1) is a 101-amino acid protein that must interact with a 59-base RNA stem-loop structure, called the traus-activation region (Tar) at the 5 end of all nascent HlV-1 mRNA molecules, in order for the vims to replicate. HIV-Tat is actively transported across the cell membrane, and localizes to the nucleus [28]. It has been found that the arginine-rich Tar-binding region of the Tat protein, residues 49-57 (Tat+9 57), is primarily responsible for this translocation activity [29]. 

Parallel to our group, a few other researchers also performed significant studies on anticancer (3-lactams. For example, (3-lactam derivatives (Fig. 2) induced DNA damage, inhibited DNA replication, and activated the apoptotic death program in human leukemic Jurkat T cells in a time and concentration-dependent manner. Importantly, (3-lactam 69 also inhibited proliferation and induced apoptosis in other human solid tumor cell lines (breast, prostate, and head-and-neck). It was believed that induction of apoptosis by 69 is associated with activation of p38 mitogen-activated protein (MAP) kinase, release of mitochondrial cytochrome c, and activation of the caspases. It was reported that apoptosis is blocked by a specific inhibitor to p38 kinase, implicating p38 MAP kinase as the major factor in (3-lactam-induced apoptosis [154]. This study was very significant. 

Huber, M., Watson, K.A., Selinka, H.C., Carthy, C.M., Klingel, K., McManus, B.M., and Kandolf, R. (1999). Cleavage of RasGAP and phosphorylation of mitogen-activated protein kinase in the course of coxsackievirus B3 replication. J Virol 73, 3587-3594. 

Protease inhibitors work by preventing cleavage of viral polyproteins into active proteins, which takes place during HIV s insidious and complicated replication process. The drug binds to the enzyme s active site, blocking cleavage of the polyprotein. 

One might say that the maintenance of replication is not surprising at all, since a gene for the DNA polymerase is included in the beginning. However, enzyme with such catalytic activity is rare. Indeed, with mutations some proteins that lost such catalytic activity but are synthesized in the present system could appear, which might take over the system. Then the self-replication activity would be lost. In fact, this is nothing but the error catastrophe by Eigen, discussed in Section n.A. Then, why is the self-replication activity maintained in the present experiment ... 

Da. The toxins are made up of two polypeptide chains (A and B) connected by a disulfide bond. The cytotoxicity of ricin is due to inhibition of protein synthesis, caused when the B chain binds to cell-surface receptors and the toxin-receptor complex is taken into the cell, and the A chain that has endonuclease activity and, at extremely low concentrations, will inhibit DNA replication and protein synthesis (USAMRICD, 2005). Ricin is stable under ambient conditions and can be detoxified by heat at 80°C for 10 min, or 50°C for an hour at a pH of 7.8. Chlorine inactivates over 99.4% by 100 mg/L FAC in 20 min. Low chlorine concentrations, such as 10 mg/L FAC, as well as iodine at up to 16 mg/L will have no effect on ricin (USAMRICD, 2005). 

Specific delivery of agents to HIV infected cells may be accomplished in two ways delivery via HIV-encoded structures on infected cells, whereby the HIV envelope proteins (gpl60 precursor, gpl20 extracellular, and gp41 transmembrane, collectively referred to as Env) are the sole virus-encoded structures found on the surface of HIV-infected cells or delivery to cellular subsets where HIV is known to replicate. Activated T cells, bearing the interleukin-2 (IL-2) receptor, are the primary cellular sites of HIV replication. 

The second system induces a rapid death of the cell by apoptosis if viral proteins are being synthesized in that cell. This second system permits the destruction of any HIV-1 infected cell, no matter whether the provirus was formerly active or silent The active provirus is detected by the presence of Rev active proteins. As this protein is involved in the rapid transport of the transcripts to the cytoplasm, avoiding or reducing the rate of splicing of the introns, its activity is essential for a correct viral gene expression, so no replication-competent viruses can escape from its detection. An apoptotic gene, p53, is inside an intron that can only be over-expressed through the 5 -LTR promoter of the vector and the presence of the Rev protein otherwise, it is... 

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