Proteins repressive complex

B. cAMP is involved in catabolite repression. Bacterial cells preferentially use glucose. When glucose is low, cAMP rises. cAMP binds to a protein and complexes near the lac promoter region, facilitating binding of RNA polymerase. Lactose must be present to inactivate the repressor, so that the operon may be expressed. 

In the human tumor, prostate adenocarcinoma, the PRC 17 protein (polycomb group repressive complex) is encoded from the 17ql2 amplicon [524]. The PRC (prostate cancer) protein contains a GTPase-activating protein GAP domain related to the yeast ceU cycle regulators Bub2 and the RabA tp-specific GTPase activator... 

There has been a recent explosion of studies regarding the functional activities associated with co-repressor molecules. While originally defined as nuclear receptor co-repressors, we now know that these proteins interact with a variety of factors. N-CoR and SMRT have been characterized as part of a multi-subunit repression complex [49, 50]. Independent of nuclear receptor interaction, N-CoR interacts with mSin3A and B, mammalian homologues of the yeast transcriptional repressor Sin3 [51]. Also in this complex are proteins which exhibit histone deacetylase activity. It has been demonstrated that co-repressor and co-activator molecules are... 

Interactions between proteins and nucleic acids are of central importance in molecular biology. Acid proteins, basic proteins form complexes with single and double stranded polynucleotides, called chromatines, which form the fundamental structure of the chromosomes. A structure conserving and stabilizing function has been attributed to the basic proteins, however, it appears that they are responsible for the more general function of gene repression (49),... 

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