EMQ 3. Theme: Eukaryotic transcription factors
From the options below, identify the eukaryotic transcription factor described in each of the items in the list.
A Bicoid
B E2F
C Glucocorticoid hormone receptor
D NFAT
E p53
F STATs
G Transcription factor IID (TFIID)
1. Found as a phosphorylated protein in the cytosol of unstimulated cells, but moves to the nucleus when dephosphorylated.
Your Answer:
Your Answer:
Answer: D, NFAT. NFAT is dephosphorylated by the phosphatase calcineurin, which is activated by calcium:
calmodulin. Dephosphorylation of NFAT reveals a nuclear localization sequence. See book page 266 and Medical Relevance 10.1 on book page 161.
2. Found in the cytosol of unstimulated cells, but moves to the nucleus when it binds a small molecule that crosses into
the cell from the extracellular medium.
Your Answer:
Your Answer:
Answer: C, the glucocorticoid hormone receptor. See book page 94.
3. Found in the cytosol of unstimulated cells, but moves to the nucleus when the concentration of calcium in the cytosol increases.
Your Answer:
Your Answer:
Answer: D, NFAT. NFAT is dephosphorylated by the phosphatase calcineurin,
which is activated by calcium: calmodulin. Dephosphorylation of NFAT reveals a nuclear localization sequence.
See book page 266 and Medical Relevance 10.1 on book page 161.
4. Found in the cytosol of unstimulated cells, but moves to the nucleus when phosphorylated on a tyrosine residue.
Your Answer:
Your Answer:
Answer: F, STATs. Each STAT protein has an SH2 domain that binds to phosphotyrosine
on a second STAT. The dimer is an active transcription factor upregulating genes important in cell proliferation.
STATs are particularly important in the immune system. See book page 264.
5. Is a multiunit protein, one of whose subunits is the TATA binding protein (TBP) that binds to the
TATA box located in the promoter region of most eukaryotic genes.
Your Answer:
Your Answer:
Answer: G, transcription factor IID (TFIID). TFIID recruits the other members of the transcription
preinitiation complex which then recruits RNA polymerase II that can then begin transcription. See book page 92.
6. Is destroyed soon after synthesis in normal, undamaged cells. DNA damage causes activation of kinases that
phosphorylate the transcription factor, preventing its breakdown and allowing transcription of genes to whose promoter this transcription factor binds.
Your Answer:
Your Answer:
Answer: E, p53. This mechanism is described on book page 306. For more on the central role of p53 in
the response to DNA damage and the elimination of potentially cancerous cells see in addition book pages 308 and 311, example 18.3
on book page 309, and {link to web box Chapter 18 / Web text box / p53: all that stands between us and cancer?}.
7. Is found in the cytosol of mitotically quiescent cells (that is, cells in G0)
but moves to the nucleus when its binding partner, the retinoblastoma protein (Rb) is phosphorylated.
Your Answer:
Your Answer:
Answer: B, E2F. See book page 305.
8. Is non-uniformly distributed in the unfertilized insect egg. Regions with high concentrations of this transcription factor become the head
Your Answer:
Your Answer:
Answer: A, bicoid. See book page 279.
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