Concept explainers
Transcription factors play key roles in the regulation of gene expression, but to do so, they must act within the nucleus. Like most proteins, however, transcription factors are translated in the cytoplasm. To enter the nucleus, transcription factors contain nuclear localization signals, which in some cases can work only when bound to some other molecule such as a steroid hormone. After entering the nucleus, transcription factors must bind to appropriate DNA sites and must interact with other transcription proteins at promoters, enhancers, and silencers. Transcription factors then activate or repress transcription through their activation or repression domains. Many drug therapies target transcription factors. Based on the information provided above, suggest three specific mechanisms through which a successful drug therapy, targeted to a transcription factor, might work.
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Concepts of Genetics (12th Edition)
- Transcription factors function in the nucleus. However, like (almost) all eukaryotic proteins,they are translated in the cytosol. Can you draw a visual to explain how transcription factor proteinsenter the nucleus from the cytoplasm? Can you also include a representation of relevant proteins and proteindomains to explain how these proteins reach their destination. Thank youarrow_forwardIn eukaryotic cells, which of the following is typical of how transcription is regulated? Group of answer choices Activators and enhancers at sites distant from structural genes interact to increase or decrease transcription Regulatory genes are always tightly coupled in physical proximity to the structural genes they regulate There are only a few transcription factors that are functional in eukarya Attenuation, where translation and transcription are tightly coupled, is common.arrow_forwardAs discussed in Lipids 3, SREBPs are a type of transcription factor involved in lipid homeostasis. SREBPs regulate the expression of genes that encode for anabolic enzymes. Normally SREBPs are degraded within 3 hours. Pancreatic cancer cells prevent this from happening, which increases cholesterol production within the tumor. If maintaining SREBPs for a longer period of time increases lipid synthesis, then these transcription factors are: O introducing a point mutation within the mRNA, causing the ribosome to synthesize a better protein binding to the promoter and preventing RNA polymerase from accessing the transcription start site introducing a premature stop codon within the mRNA, causing the ribosome to terminate translation binding upstream of the promoter and recruiting RNA polymerase to the transcription start site binding to the origin of replication and recruiting DNA polymerase for bidirectional synthesisarrow_forward
- What are general transcription factors? When do you expect to find them? What is a cis acting regulatory sequence? Where are they located in comparison with the gene they are regulating?arrow_forwardProgesterone is a steroid hormone (also described as a ligand) that prepares the body for pregnancy. It binds to the progesterone receptor (PR) protein in the cytoplasm of various cells. Ligand bound PR acts as a transcriptional activator, binds to the DNA in the promoter region of several genes and leads to transcriptional activation of these genes. Which of the following statements must be true for the PR protein? O Ligand binding to the PR results in a conformational change in the primary structure of the protein The domain/region of the PR protein that interacts with the DNA, has basic amino acids Ligand binding to the PR results in a conformational change in the tertiary structure of the protein The domain/region of the PR protein that interacts with the DNA, has acidic amino acidsarrow_forwardDiscuss the following argument: “if the expression of every gene depends on a set of transcription regulators, then the expression of these regulators must also depend on the expression of other regulators, and their expression must depend on the expression of still other regulators, and so on. cells would therefore need an infinite number of genes, most of which would code for transcription regulators.” how does the cell get by without having to achieve the impossible?arrow_forward
- What is the role of general transcription factors? GTFs bind to enhancers or silencers and regulate transcription GTFs bind to the core promoter and allow transcriptional initiation GTFs are cis-acting regulatory sequences GTFs regulate the length of the mRNA GTFs are part of the RNA polymerase II holoenzyme, and control transcription initiationarrow_forwardA TATA box is a short, A-T rich sequence of nucleotides located just upstream of genes and is used to recruit transcription factors and RNA polymerase to begin transcription. Based on this description, a TATA box is most likely a(n): promoter terminator transcription factor RNA polymerasearrow_forwardThe binding of a small effector molecule, protein-protein interactions, and covalent modifications are three common ways to modulate the activities of transcription factors. Which of these three mechanisms are used by steroid receptors and by the CREB protein?arrow_forward
- Which of the following is NOT a reason cells regulate gene expression at a level other than the transcriptional level? Some proteins are only required in part of the cell and transcriptional control will only regulate the mRNA/protein throughout the cell. The core promoter for many genes is the same, so these genes will always be transcribed in the same cells. Differential gene expression in different cell types requires regulation of gene expression at levels other than transcription. Transcription and translation are realtively slow processes, so cells need to regulate gene expression post-transcriptionally if they require a fast change in expression of a gene. Not all cells are transcriptionally active (meaning they do not transcribe any genes), so these cells need to regulate gene expression post-transcriptionally.arrow_forwardWhich of the following functions are characteristic of general transcription factors in eukaryotes? Hint: there may be more than one correct response. Be sure to check all that apply. They inhibit RNA polymerase binding to the promoter and begin transcribing. They bind to other proteins or to the TATA box. They are sufficient to allow high levels of transcription. O They initiate and regulate the transcription of genes. O They bind to sequences just after the start site of transcription.arrow_forwardDiscuss how the expression of a protein can be regulated post transcription in eukaryotic cells through, using the following key terms: Degradation of mRNA (two ways) Blocking translation Degradation of the proteinarrow_forward
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