BIOL 367 Chapter Notes - Chapter 12: Lac Operon, Restriction Enzyme, Peroxidase
Document Summary
Transcription activators (gene specific transcription factors) and enhancers (the binding sites for gene specific transcription factors) in eukaryotes. Heterochromatin = highly condensed and inaccessible to rna polymerases, so it cannot be transcribed. Euchromatin = still contains protein, but is relatively extended. Activators can either stimulate or inhibit transcription by. They have structures composed of at least 2 functional domains: a dna binding domain and a transcription- activating domain. Many also have a dimerization domain that allows the activators to bind to each other (homodimers, heterodimers, higher multimers) Some even have binding sites for effector molecules (steroid hormones) Each dna-binding domain has a dna-binding motif, which is the part of the domain that has a characteristic shape specialized for specific dna binding. Most activators have one of these domains, but some have more than one: acidic domains ex. yeast activator gal4, glutamine-rich domains ex sp1 has two, proline rich domains ex.
