Transcription factors function

Prochiantz A, Joliot A (2003) Can transcription factors function as cell-ceU signaUing molecules Nat Rev Mol Cell Biol 4 814-819... 

In plants, DREB/ERF and AP2/ERF subfamily of ethylene-responsive element (GCC box)-binding transcription factors function in the regulation of abiotic stress responses and regulate disease resistance. AP2/ERF members are downstream components of both ethylene and JA signaling pathways, and are key to the... 

Of particular importance is the phosphorylation of eucaryotic transcription factors. Functional and mechanistic consequences of the phosphorylation of transcription factors will be discussed in more detail in the section on the regulation of eucaryotic transcription (see 1.4.3.2). Specific or non-specific protein phosphatases (see 7.5) can remove the phosphate residues and terminate the phosphorylation signal. 

Nasir ud D. Oct-2 DNA binding transcription factor functional consequences of phosphorylation and glycosylation. Nucleic Acids 36. 

T-cell subset Cytokines produced Lineage-specific transcription factor Functions... 

Metalloporphyrins, characterized by a redox-active transitional metal coordinated to a cyclic porphyrin core ligand, mitigate oxidative/nitrosative stress in biological systems. Side-chain substitutions tune redox properties of metalloporphyrins to act as potent superoxide dismutase mimetics, peroxynitrite decomposition catalysts, and redox regulators of transcription factor function. Metalloporphyrins are efficacious in AD models [538],... 

Liu, C B.M. Smith, K. Ajito, H. Komatsu, L. Gomezpaloma, T.H. Li, E.A. Theodorakis, K.C. Nic-olaou, and P.K. Vogt (1996). Sequence selective carbohydrate DNA interaction dimeric and monomeric forms of the calicheamicin oligosaccharide interfere with transcription factor function. Proc. Natl. Acad. Sci. USA 93 940-944. 

Modulation of activator and repressor function by effector molecules. Repressors can either be inhibited (A) or stimulated (B) by effector-molecule interactions. Similarly, activators can either be stimulated (C) or inhibited (D) by effector-molecule interactions. Transcription-factor functions can also be modulated by posttranslational modification such as phosphorylation (see Fig. 29.10). 

One of the best examples of dimerization control of transcription-factor function is the interaction of basic helix-loop-helix (bHLH) proteins. Figure 29.5 shows that the interaction between various bHLH proteins can be reflected in the affinity of homo- and heterodimers for specific DNA sequences. Helix-loop-helix proteins lacking the basic region required for DNA binding, can dimerize with bHLH proteins and inhibit their DNA binding activity. These HLH proteins are said to have a dominant negative effect on bHLH proteins because they are dominant repressors of bHLH activity (Fig. 29.5). 

Effector A small molecule that regulates the function of a protein cAMP is a positive effector of CAP transcription-factor function and protein kinase A activity. 

Leucine zipper transcription factors function as homodimers or heterodimers. For example, API is a heterodimer whose subunits are encoded by the genes fos and jun. 

Figure 4.30 Proposed mechanisms for bZIP transcription factor function. Stable association of the bZIP dimer with DNA can occur via a monomer or dimer pathway. Binding of both monomer and dimer is diffusion limited. Analysis of the kinetics of both pathways suggests that the monomer pathway may have an overall kinetic advantage.

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