Transcription of the Eukaryotic Genome II

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The proteins involved in transcription in eukaryotes
(1) the basic transcription apparatus and associated factors (also known as general or basal transcription factors)
(2) Multi-subunit coactivators(mediator) and other cofactors;
(3) sequence-specific DNA-binding transcription factors; and
(4) chromatin-condensation related proteins.


Transcription is catalyzed by RNA polymerase
• Catalyzes the synthesis of RNA directed by
DNA as a template = transcription
•Makes an RNA chain with a sequence
complementary to the template strand of
DNA
•Does NOT require a primer; can start RNA
synthesis at a site on the DNA template



Sequence-specific DNA-binding transcription factors
(activators and repressors).
Proteins that show sequence-specific DNA binding and are capable of activating and/or repressing tx.
Most numerous of all the groups of proteins involved in tx.



Conserved domains of common transcription
Leucinezipper
Protein binding domain: Stretches of 35 amino acids in which Leuis found repeatlyat intervals of 7 amino acids, forming amphiphilichelices, with Leuon one face. Two of these proteins can form a dimer, stabilized by the binding of these amphiphilichelices to one another, forming a coiled-coil.
The DNA binding domain is found in the first 30 N-terminal amino acids, which are basic and form an alpha helixwhen the protein binds to DNA. The leucinezipper then functions to bring two DNA binding proteins together, allowing the N-terminal bases helices to interact with the major grove of DNA in a base-specific fashion.