Repressor gene

CtsR/CtsR box (class three stress gene repressor)... 

Lytic growth of Mu can occur either upon initial infection, if the c gene repressor is not formed, or by induction of a lysogen. In either case, replication of Mu DNA involves repeated transposition of Mu to multiple sites on the host genome. Initially, transcription of only the early genes of Mu occurs, but after gene C protein, a positive activator of late RNA synthesis, is expressed, the synthesis of the Mu head and tail proteins occurs. Eventually, expression of the lytic function occurs and mature phage particles are released. 

Until rather recently there had been little to indicate that DNA actually assumes cruciform conformations in cells. However, strong experimental evidence suggests that some cruciform structures do form naturally.380 Their formation from palindromic DNA [like the formation of Z-DNA from (G + C)-rich sequences] is a way of relieving torsional strain induced by super-coiling. Whether or not cruciform structures occur frequently within cells, there is no doubt that palindromic sequences are of great importance in the interaction of nucleic acids with symmetric dimeric and tetrameric protein molecules such as the gene repressor protein shown in Fig. 5-35.381-383... 

Other nonhistone nuclear proteins. Polyacrylamide gel electrophoresis revealed more than 450 components in HeLa cell nuclei. Most are present in small amounts of <10,000 molecules per cell and are not detectable in cytoplasm.112 Among the more acidic proteins are many enzymes including RNA polymerases. There are also gene repressors, hormone-binding proteins, protein kinases, and topoi-somerases.113 Among the six most abundant nonhistone nuclear proteins in the rat are the cytoskeletal proteins myosin, actin, tubulin, and tropomyosin.114... 

Proteins that serve as gene repressors frequently have two identical binding sites that interact with complementary sites on the DNA. If a repressor protein is... 

Schematic model illustrating the operon hypothesis. This diagram is modified from the original proposed by Jacob and Monod, who thought i gene repressor was an RNA rather than a protein, (a) The i gene encodes a repressor that binds tightly to the operator o locus, thereby preventing transcription of the mRNA from the z, y, and a structural genes. (b) When inducer is present, it combines with repressor, changing its structure so it can no longer bind to the operator locus. Inducer also can remove repressor already complexed with the o locus.

Repressors Gene repressor proteins that inhibit the transcription of specific genes in eukary-... 

Know the roles of a regulator gene, repressor and corepressor, catabolite gene activator protein (CAP), cyclic AMP, and attenuator. 

According to this model, the infusion of hemophilic plasma into a patient with von Willebrand s disease would increase the plasma concentration of effector, which in turn would block the action of the hemophUia-gene repressor toward a normal level of activity, and thus increase the synthesis of factor VIII by the X-chromosome operon. A crucial implication is that the transfusion effect should operate in the same way whether the von Willebrand patient is heterozygous or homozygous, for in either case his (or her) normal X-chromosome operon should synthesize normal factor... 

VIII when the hemophilia-gene repressor is blocked by the infused effector. Another phenomenon explicable by this model is discussed below (Section 3.5.2). 

Fujioka, M., et al. 1999. Analysis of an even-skipped rescue transgene reveals both composite and discrete neuronal and early blastoderm enhancers, and multi-stripe positioning by gap gene repressor gradients. Development 126 2527-2538. 

Biotin is central to the metabolism of carbohydrates, amino acids, and lipids as biotin is the prosthetic group of the carboxylases. In addition to this metabolic function, biotin influences transcription in organisms ranging from bacteria to humans. Biotin exerts complex effects on cell cycle and gene transcription through epigenetic mechanisms. Nuclear biotin holocarboxylase synthetase seems to interact with other chromatin proteins to form a multiprotein gene repressor complex. 

These experiments thus reveal a dual type of control, a primary determination (synthesis of early forms of RNA and passiveness of the late genes) predetermined by the actual DNA structure. The changeover to synthesis of late proteins cannot take place without preliminary synthesis of early proteins. No evidence has yet been found to suggest that the synthesis of a particular protein, such as a gene repressor or activator, is essential for this purpose. 

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