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Figure 1 | BMC Biochemistry

Figure 1

From: DNA binding reduces the dissociation rate of STAT1 dimers and impairs the interdimeric exchange of protomers

Figure 1

Graphic illustration of putative pathways for the interconversion of parallel and antiparallel STAT1 conformers. The domain structure of STAT1 is marked with different colours: the N-terminal domain (N, green) is added via a short flexible segment to the core fragment comprising the coiled-coil domain (C, yellow), the DNA-binding domain (D, blue), the linker domain (not shown), the SH2 domain (S, orange), and the carboxyterminal transactivation domain (not shown). The interface in the antiparallel dimer is formed by reciprocal binding between the coiled-coil domain of one protomer and the DNA-binding domain of the partner protomer, while in the parallel dimer there are reciprocal interactions between the phospho-tyrosine residue 701 (P, marked as red circles) and the SH2 domain. Model 1 (top left) assumes that the core domains of the two partner protomers rotate around each other facilitated by reciprocal N-terminal interactions [21,22]. In contrast, the dissociation/re-association model (model 2, bottom left) allows the formation of new dimer combinations and does not require the presence of the N-terminal domain [23]. Addition of specific DNA-binding elements termed gamma-activated sites (GAS, marked in red) results in the formation of STAT1 dimers bound to a single GAS site (top right) or STAT1 tetramers when complexed with two GAS sites arranged in a tandem orientation (bottom right).

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