Protein transcriptional control

Regulatory regions are transcriptional control sequences, which consist of promoters, response elements, enhancers and possibly silencers, located upstream of the start site of transcription. The overall effect on gene transcription is a sum of the contributions of these elements and the activities of proteins recruited to these sites. Promoters are located immediately upstream of the start site and initiate transcription. They often contain tissue- or cell-specific elements if the gene is not ubiquitously expressed. Enhancers are positive regulatory elements which function independently of orientation and distance from the genes they regulate. 

Transcription controls operate at the level of protein-DNA and protein-protein interactions. These interactions display protein domain modularity and high specificity. 

Point mutations Protein folding Transcriptional control Frameshiftand nonsense mutations RNA processing Sickle cell disease P-Thalassemia P-Thalassemia P-Thalassemia... 

The SCF and SCF-like complexes are multi-subunit RING-type E3s that represent the largest E3 family knotvn to date. This superfamily of E3s are involved in regulating cell-cycle progression, signal transduction pathways, transcriptional control, and multiple aspects of cell growth and development (reviewed in Ref. [50]). All members of this E3 superfamily contain two basic components, a member of the cullin protein family and a RING-domain protein. The cullin subumt serves as the... 

Methylation plays an important role in transcriptional regulation and a lesser role in signal transduction. " Histones are heavily methylated proteins. Single, double, or triple methylated lysines play an important role on histones. Lysine methylation is a more subtle transcriptional control than acetylation. Lysine methylation has come to light in another protein known as p53. p53 is a protein expressed in low levels in the cell and stabilized by posttranslational modifications including phosphorylation, acetylation, and now N-methylation. There are several C-terminal lysines on p53 that increase its stability. The addition of the methylation modifications adds complexity to p5 3 and fine-tunes its activity and ultimately suppresses tumor formation. ... 

From a different perspective, circumstantial evidence suggests that ADPr may have a functional role in the activation of transcription. PARP copurifies with TFnC [230] and upregulates AP-2 (Activator Protein 2) controlled transcription. However, these results need to be interpreted cautiously, as a molecular mechanism for ADP-ribosylation of targeted histones has yet to be identified. 

Regulatory proteins (transcription factors) are involved in controlling gene expression in all cells. These regulatory proteins bind to specific DNA sequences and thereby activate or inhibit the transcription of genes (Transcription control). The effects of transcription factors are usually reversible and are often controlled by ligands or by interconversion. 

The well-investigated lactose operon of the bacterium Escherichial coli can be used here as an example of transcriptional control. The lac operon is a DNA sequence that is simultaneously subject to negative and positive control. The operon contains the structural genes for three proteins that are required for the utilization of lactose (one transporter and two enzymes), as well as control elements that serve to regulate the operon. 

Lipophilic signaling substances include the steroid hormones, calcitriol, the iodothy-ronines (T3 and T4), and retinoic acid. These hormones mainly act in the nucleus of the target cells, where they regulate gene transcription in collaboration with their receptors and with the support of additional proteins (known as coactivators and mediators see p.244). There are several effects of steroid hormones that are not mediated by transcription control. These alternative pathways for steroid effects have not yet been fully explained. 

An example of specific transcriptional control is cyclic AMP-dependent regulation of genes that have a cyclic AMP response element (CRE) through the action of the transcription factor CREB (cyclic AMP response element binding protein. Figure 12-5). 

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