Gene expression Flashcards
Helix turn helix proteins
2 alpha helices connected by a short strand of amino acids. C terminal helix is recognition helix. Binds DNA as dimers.
Leucine zipper proteins
2 alpha helices held together by hydrophobic interactions of amino acid side chains. Binds DNA as dimers.
Homeodomain proteins
3 alpha helices held together by hydrophobic interactions, helix one forms contact with minor groove too.
Beta sheet DNA recognition proteins
2 stranded beta sheet reads info from major groove.
Zinc finger proteins
Zinc atom holds alpha helix and beta sheet together.
Helix loop helix proteins
Short alpha helix connected to long alpha helix by a loop. Creates homo or heterodimers.
Heterodimers
Can regulate combinations of proteins that bind to different sequences.
Regulatory sequence
Binds a protein that increases or decreases activity of the gene.
Operons are…
Common in bacteria but rare in eukaryotes.
Tryptophan repressor
Transcription regulator, recognizes cis regulatory sequence in operons promoter.
Tryptophan operator
Cis regulatory sequence.
Activator
Makes poorly functioning promoter works well by binding near by cis reg proteins and contacting the RNA polymerase to help initiate transcription.
How are genes activated by CAP turned on?
In response to an increase in intracellular cAMP.
When does cAMP increase?
When there is no glucose.
What is the lac operon controlled by?
Lac repressor and CAP activator
