武汉大学分子考研本科生教学2008chater17培训资料.ppt

* SWI5: acts only in the mother cell and binds to multiple sites some distance from the gene unaided, which recruit enzymes to open the SBF binding sites. SBF: only active at the correct stages of the cell cycle, and cannot bind the sites unaided. Alter the nucleosome Figure 17-15 (组蛋白 乙酰化酶) * Figure 17-14: Cooperative binding of activators. (c) The first protein recruit a nucleosome remodeller whose action reveal a binding site for the second protein. * 3. Signal integration: Cooperative binding of activators at the human b-interferon gene. [S3策略的example] The human b-interferon gene (target gene) is activated in cells upon viral infection (signal). Infection triggers three activators (communicator): NFkB, IRF, and Jun/ATF. Activators bind cooperatively to sites adjacent to one another within an enhancer located about 1 kb upstream of the promoter, which forms a structure called enhanceosome. * Figure 17-16 增强体 (人的b干扰素基因) 增强子 Activators interact with each other HMG-I binds within the enhancer and aids the binding of the activators (bends the DNA to promote the activator interaction) * HMG-I is constitutively active in the cells, and play an architectural role in the INF-b gene activation process. * Figure 17-14: Cooperative binding of activators. (a)“Classical” cooperative binding through direct interaction between the two proteins. * 4. Combinatory control (组合调控) lies at the heart of the complexity and diversity of eukaryotes, in which Both activators and repressors work together. 组合调控是真核生物复杂性和多样性的核心。它属于协作调控的一种具体方式。在组合调控中，激活蛋白和阻遏蛋白共同起作用。 * A regulator (CAP) works together with different repressors at different genes, this is an example of Combinatorial Control. In fact, CAP acts at more than 100 genes in E.coli, working with an array of partners. 7: Combinatorial Control (组合调控): CAP controls other genes as well Page 499 Slide 47 in Ch 16 Review * In complex multicellular organisms, combinatorial control involves many more regulators and genes than shown