Chan S K, Jaffe L, Capovilla M, Botas J, Mann R S
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032.
Cell. 1994 Aug 26;78(4):603-15. doi: 10.1016/0092-8674(94)90525-8.
The Ultrabithorax (Ubx) and Antennapedia (Antp) genes of Drosophila encode homeodomain proteins that have very similar DNA binding specificities in vitro but specify the development of different segmental patterns in vivo. We describe cooperative interactions between Ubx protein and a divergent homeodomain protein, extradenticle (exd), that selectively increases the affinity of Ubx, but not Antp, for a particular DNA target. We also provide evidence that Ubx and exd bind to neighboring sites on this DNA and interact directly to stabilize the DNA-bound form of Ubx. Thus, the ability of different homeotic genes to specify distinct segmental patterns may depend on cooperative interactions with proteins such as exd that selectively modulate their otherwise similar DNA binding specificities.
果蝇的超双胸（Ubx）基因和触角足（Antp）基因编码的同源异型结构域蛋白，在体外具有非常相似的DNA结合特异性，但在体内却决定着不同的体节模式发育。我们描述了Ubx蛋白与一种不同的同源异型结构域蛋白——额外齿（exd）之间的协同相互作用，这种相互作用选择性地增加了Ubx对特定DNA靶点的亲和力，而对Antp则没有这种作用。我们还提供了证据表明，Ubx和exd结合在该DNA上的相邻位点，并直接相互作用以稳定Ubx与DNA结合的形式。因此，不同的同源异型基因决定不同体节模式的能力，可能取决于与诸如exd这类能选择性调节其原本相似的DNA结合特异性的蛋白质的协同相互作用。
