Transactivation-responsive region

The transactivation-responsive region (TAR) is located immediately downstream of the transcriptional start site in the HIV-1 LTR, encompassing nucleotides h-1 to h-59 (Berkhout et al. 1989 Muesing et al. 1987), and is reqnired for the function of the viral trans-activator protein Tat. In the absence of Tat (Fig. 5.2b), short transcripts... 

Fig. 7.4 The HIV-1 lentiviral-based vector contains the 5 long terminal repeat (5 -LTR), transactivation response region (TAR), packaging sequence (0), primer binding site (pbs), splice donor (SD) and acceptor (SA) sites, Rev response element (RRE), the 3 long terminal repeat (3 -LTR) and the polypurine tract (ppt) from HIV-1. It contains a cassette with the tat cDNA placed under the LacS-witch II inducible mammalian expression system...

Ippolito JA, Steitz TA (1998) A 1.3-A resolution crystal structure of the HIV-1 transactivation response region RNA stem reveals a metal ion-dependent bulge conformation. Proc Natl Acad Sci USA 95(17) 9819-9824... 

Fig. 18.20. Left In vitro binding site of the basic subdomain of human immunodeficiency virus type-1 (HIV-1) transactivator protein (Tat) in the transactivation response (TAR) RNA sequence. Only a short portion of the stem region of TAR is shown. Sites where residue modification interferes with Tat binding (the putative binding site) are bold. They comprise part of the pyrimidine bulge and the adjacent duplex, but not the hairpin loop, shown at the top. The boxed base U24 enhances binding when eliminated, whereas modification of C23 does not interfere with peptide binding. The dashed line connecting C and G in the six-base loop indicates the possible formation of a base pair.

Estrogen receptor alpha and ERp consist of a hypervariable N-terminal domain that contributes to the transactivation function (A/B), a highly conserved central domain responsible for specific DNA binding, dimerization, and nuclear localization (C), an estrogenbinding domain (E), a hinge region domain (D), and a domain (F) whose function is not known (Tonetti and Jordan, 1997). 

The form of vitamin A that is needed for regulating vitamin A-dependent gene expression is retinoic acid.All-fraws-retinoic acid can interact with each of the three RARs (RARa, RAR(3, and RARy) and each of the three RXRs (RXRa, RXR(3, and RXRy). 9-cX-Retinoic acid binds and effectively transactivates only the RXRs. The RARs and the RXRs recognize well-defined exacting response elements, termed retinoic acid response elements (RAREs) and retinoid X response elements (RXREs) that are present in the promoter regions of responsive genes. The RARs and RXRs bind to RAREs and/or RXREs as dimers, either homodimers or heterodimers. 

The regulatory regions of mammalian and yeast MTs have been studied in detail, but less is known about fish MT promoter regions. A hallmark of MTs is the rapid transactivation through multiple copies of metal responsive elements (MREs) within... 

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