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Figure 6.
Figure 6. Model for Selective Recruitment of Cofactors by
POU DimersSchematic representation of POU dimer arrangements
bound to (A) the PORE; (B) the MORE (Oct-1) or Prl (Pit-1); and
(C) the MORE^+2 (Oct-1) or GH (Pit-1) DNA response elements,
which contain a 2 base pair insertion between the two
half-sites when compared to MORE/Prl. The different quaternary
arrangements of POU subdomains (indicated by spheres) either
expose or bury the MORE- or the PORE-type dimerization
interfaces. The MORE-type interface is indicated as rectangular
indentations (on the surface of POU[S]) and protrusions (on the
surface of POU[H]). The PORE-type interface is indicated by
triangles. The open MORE-type interface is used for binding of
OBF-1 in the Oct-1/PORE dimer. On the other hand, the PORE-type
interface could be potentially engaged for specific cofactor
recruitment (“Y” and “Z”), which could either be
selective with respect to the type of dimer configuration (MORE
versus PORE) or to the spacing of half-sites within one
configuration. The second type of selectivity is only applicable
for the MORE configuration, because the PORE configuration does
not allow different spacing of DNA half-sites. The N-CoR
corepressor complex (Scully et al., 2000) selectively binds to
Pit-1 in complex with GH (“Z”) but not with Prl (“Y”)
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