第二十一章 转录的调控(Regulation

Figure 21.1 The regulatory region of a human metallothionein gene contains regulator elements in both its promoter and enhancer. The promoter has elements for metal induction; an enhancer has an element for response to glucocorticoid. Promoter elements are shown above the map, and proteins that bind them are indicated below.
21.5 Steroid receptors have several independent domains
Figure 21.7 Glucocorticoids regulate gene transcription by causing their receptor to bind to an enhancer whose action is needed for promoter funny types of DNA-binding domains
Figure 21.2 The activity of a regulatory transcription factor may be controlled by synthesis of protein, covalent modification of protein, ligand binding, or binding of inhibitors that sequester the protein or affect its ability to bind to DNA.
21.5 Steroid receptors have several independent domains
Figure 21.6 Several types of hydrophobic small molecules activate transcription factors. Corticoids and steroid sex hormones are synthesized from cholesterol, vitamin D is a steroid, thyroid hormones are synthesized from tyrosine, and retinoic acid is synthesized from isoprene (in fish liver).
21.1 Introduction
Activation of gene structure Initiation of transcription Processing the transcript Transport to cytoplasm Translation of mRNA
21.2 Response elements identify genes under common regulation
Regulatory Agent Module Heat shock Glucocorticoid Phorbol ester Serum HSE GRE TRE SRE Consensus CNNGAANNTCCNNG TGGTACAAATGTTCT TGACTCA CCATATTAGG Factor HSTF Receptor AP1 SRF
Chapter 21
Regulation of Transcription
21.1 Introduction 21.2 Response elements identify genes under common regulation 21.3 There are many types of DNA-binding domains 21.4 A zinc finger motif is a DNA-binding domain 21.5 Steroid receptors are transcription factors 21.6 Steroid receptors have zinc fingers 21.7 Binding to the response element is activated by ligand-binding 21.8 Steroid receptors recognize response elements by a combinatorial code 21.9 Homeodomains bind related targets in DNA 21.10 Helix-loop-helix proteins interact by combinatorial association 21.11 Leucine zippers are involved in dimer formation 21.12 Transcription initiation requires changes in chromatin structure 21.13 Chromatin remodeling is an active process 21.14 Activation of transcription requires changes in nucleosome organization at the promoter 21.15 Histone acetylation and deacetylation control chromatin activity 21.16 Polycomb and trithorax are antagonistic repressors and activators 21.17 An LCR may control a domain 21.18 Insulators block enhancer actions 21.19 Insulators can vary in strength 21.20 A domain has several types of elements 21.21 Gene expression is associated with demethylation 21.22 CpG islands are regulatory targets
21.5 Steroid receptors have several independent domains
Figure 21.5 The first finger of a steroid receptor controls specificity of DNA-binding (positions shown in red); the second finger controls specificity of dimerization (positions shown in blue). The expanded view of the first finger shows that discrimination between GRE and ERE target sequences rests on two amino acids at the base.
Table 21.1 Incucible transcription factors bind to response elements that identify groups of promoters or enhancers subject to coordinate control.
21.2 Response elements identify genes under common regulation
21.4 A zinc finger motif is a DNA-binding domain
Figure 21.5 The first finger of a steroid receptor controls specificity of DNA-binding (positions shown in red); the second finger controls specificity of dimerization (positions shown in blue). The expanded view of the first finger shows that discrimination between GRE and ERE target sequences rests on two amino acids at the base.
21.5 Steroid receptors have several independent domains
Receptor is a transmembrane protein, located in the plasma membrane, that binds a ligand in a domain on the extracellular side, and as a result has a change in activity of the cytoplasmic domain. (The same term is sometimes used also for the steroid receptors, which are transcription factors that are activated by binding ligands that are steroids or other small molecules.)
21.5 Steroid receptors have several independent domains
Figure 21.8 Receptors for many steroid and thyroid hormones have a similar organization, with an individual Nterminal region, conserved DNAbinding region, and a C-terminal hormonebinding region.