Context-dependent activation domain

Fig. IB Structural organization of the T-cell factor proteins (Tcfs). The DNA-binding HMG box and p-catenin/Armadillo binding domains are highly conserved between family members. Lef-1 contains a unique context-dependent activation domain (CAD), which is required for Lef-1-mediated TCRa enhancer activity. The greatest sequence diversity is present within the C termini, which are often generated via alternative splicing. (Ch, chicken X, Xenopus d, Drosophila).

These results show a clear distortion of substrate binding and catalytic activities upon fragmentation of the multienzymes. The substrate pocket architecture seems to depend on the context of adjacent domains as well. Although questions remain, the linearity rule of NRPS holds in ACV synthetases. Open questions remain on the fate of possibly misactivated amino acids in the terminal... 

Satellite viruses are those that are dependent for their own replication on some (catalytic) activity encoded in another helper virus that coinfects the host cell. The structures of three plant ssRNA satellite viruses represent some of the highest resolutions known and have been comparatively reviewed (Ban et al., 1995). The structures of satellite tobacco mosaic virus (STMV) (Larson et al., 1993a,b), satellite tobacco necrosis virus (STNV) (Jones and LUjas, 1984 Liljas et al., 1982), and satellite panicum mosaic virus (SPMV) (Ban and McPherson, 1995) have T=1 capsids composed of 60 identical copies of unembellished jelly-roll j3 barrels constructed of only 155 to 195 amino acids (Fig. la see Color Insert). What is remarkable is how little the assembly context of these domains is conserved. The same end always points toward the 5-fold axis, but the domains are rotated to different extents around the 5-fold axis. Furthermore, between STNV and the others, there is a 70° rotation of the barrel about its long axis. Contacts across the dimer interface are... 

Role of the two activating domains of the oestrogen receptor in the cell-type and promoter-context dependent agonistic activity of the anti-oestrogen... 

Vigano, M.A., Di Rocco, G., Zappavigna, V., Mavilio, F. 1998. Definition of the transcriptional activation domains of three human HOX proteins depends on the DNA-binding context. Mol. Cell Biol. 18, 6201-6212. 

The human PR exists as two functionally distinct isoforms PRA and PRB transcribed from two promoters from a single gene. PRA lacks the N-terminal 164 aa and is a 769 aa protein. PRB functions as a transcriptional activator in most cell and promoter contexts. In contrast, PRA is transcriptionally inactive and functions as a strong ligand-dependent transdominant repressor of SHR transcriptional activity. Different cofactor interactions were demonstrated for PRA and PRB, probably due to an inhibitory domain within the first 140 aa of PRA, which is masked in PRB. Both PR isoforms however, repress estradiol-induced ER activity when liganded. Several other mRNA isoforms are present in PR-positive tissues such as breast cancer with unknown clinical significance. 

Figure 2. Mechanisms and signalings of neuronal death. Death can be initiated at the membrane by activation of death domain receptors (DDR), or by intracellular signalings through oxidative stress (and the production of reactive oxigen species, ROS), perturbed calcium homeostasis, mitochondrial dysfunction (release of cytochrome c, cytC), activation of caspases, as well as reactivation of cell cycle genes such as the transcription factor E2F (see text). Interconnections have been demonstrated (dotted lines) depending on the apoptotic context...

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