ZOOHCC - 501: Molecular Biology (Theory)
Unit 3: Transcription and Regulatory RNAs
Unit 3: Transcription and Regulatory RNAs
Transcription factors
Transcription factors are proteins that regulate the transcription of
genes. That is, copying into RNA on the way to protein.
Explanation
Transcription factor, a molecule that controls the activity of a gene by determining whether the gene's DNA (deoxyribonucleic acid) is transcribed into RNA (ribonucleic acid). The enzyme RNA polymerase catalyzes the chemical reaction that synthesizes RNA using the DNA of a gene as a template. Transcription factors control when, where, and how efficiently RNA polymerase functions.
Transcription factors are essential not only for normal development of an organism, but also for routine cellular function and disease response. Transcription factors are a diverse family of proteins that generally function in multisubunit protein complexes. They can either bind directly to specific 'promoter' regions of DNA located upstream of the coding regions of genes, or they can bind directly to RNA polymerase molecules. Transcription factors can activate or repress the transcription of genes. This is generally a key determinant of whether a gene is functioning at a given time.
Basic or general transcription factors are required for the function of RNA polymerase at eukaryotic transcription sites. They are considered to be the most basic group of proteins required to activate gene transcription, among which many proteins such as TFIIA (transcription factor II A) and TFIIB (transcription factor II B) are It contains. Significant progress has been made in defining the role played by each protein that makes up the basal transcription factor complex. During the development of multicellular organisms, transcription factors play a role in determining the fate of individual cells. For example, homeotic genes control patterns of body formation, and these genes encode transcription factors that instruct cells to form different parts of the body. Homeotic proteins activate one gene and repress another, producing complementary effects necessary for the orderly development of the organism. If one of the homeotic transcription factors mutates, the organism will not develop properly. For example, in Drosophila, mutations in certain homeotic genes alter transcription so that legs grow on the head instead of the antennae. This is known as Antennapedia mutation. Transcription factors are a common way cells respond to extracellular information. B. Environmental stimuli and signals from other cells. Transcription factors may play important roles in cancer by influencing the activity of genes involved in the cell cycle (or cell division cycle). In addition, transcription factors can be the products of oncogenes (genes that can cause cancer) or tumor suppressor genes (genes that suppress cancer).
Transcription factors act in the nucleus, where genes are located, and nuclear transport (ie, import or export) of transcription factors can affect their activity. Another important general mechanism controlling the activity of transcription factors is post-translational modifications such as phosphorylation. Finally, these protein complexes not only regulate the transcription of genes and other transcription factors, but can also regulate genes responsible for their own transcription, resulting in complex feedback control mechanisms.
transcription factors mechanism
Activator: Some transcription factors activate transcription. For example, they can help common transcription factors and RNA polymerases bind to promoters, as shown in the diagram below.
Repressor: Other transcription factors repress transcription. This suppression works in different ways. For example, repressors interfere with basic transcription factors or RNA polymerases, preventing them from binding to promoters and initiating transcription.
Binding site: Binding sites for transcription factors are often located near the promoters of genes. However, they can also occur at other sites in the DNA, sometimes very far from the promoter, and affect gene transcription. The parts of the activator protein: the DNA-binding domain (which binds to the recognition site on DNA) and the activation domain, the activator's "shop end" that actually promotes transcription. B. By promoting the formation of transcription initiation complexes. The parts of the activator protein: the DNA-binding domain (which binds to the recognition site on DNA) and the activation domain, the activator's "shop end" that actually promotes transcription. B. By promoting the formation of transcription initiation complexes. The flexibility of DNA allows transcription factors at distant binding sites to do their job. DNA meanders like cooked spaghetti, bringing distant binding sites and transcription factors closer to a common transcription factor, or 'mediator' protein.
