FMBG 12 Signal Transduction Coupled Tx Factors

Question 0

Extracellular signals that regulate transcription factor activity must regulate:

Answer 0

a. nuclear localization, and/or b. DNA binding, and/or c. transactivation

Question 1

Describe the ribosomes that synthesize transcription factors (location, solubility)

Answer 1

Free ribosomes, soluble

Question 2

How many nuclear pore complexes per cell?

Answer 2

3000-4000 NPCs in average cell

Question 3

of Macromolecules transferred per second in a cell through nuclear pores

Answer 3

500 per sec

Question 4

What size molecules require active transport into nucleus?

Answer 4

>60,000 daltons

Question 5

Do proteins destined for the nucleus possess?

Answer 5

Nuclear localization signals

Question 6

Describe a nuclear localization signal (size, # of amino acids)

Answer 6

~5 amino acids long, usually contains Lys and Arg

Question 7

Different nuclear localization signals are recognized by families of ___________

Answer 7

Nuclear import receptors

Question 8

Gating of nuclear transport is mediated by: a) Ras b) Rho c) Ran d) Rab

Answer 8

c) Ran

Question 9

Ran most closely resembles what other G protein we learned about in detail?

Answer 9

Ras

Question 10

A key distinction between ran and ras?

Answer 10

Ran is compartmentalized across the nuclear membrane

Question 11

Binding of Ran-GTP to the cargo-import receptor complex causes ______. This happens in the ______.

Answer 11

cargo release (in the nucleus)

Question 12

Cytosol vs nucleus: Which most likely has a higher conc of GEF?

Answer 12

Nucleus

Question 13

We regulate access to nucleus by regulating access to the ________

Answer 13

Nuclear localization signal

Question 14

Current model of nuclear pore: a) Selective phase b) Oily spaghetti c) Brownian affinity gate

Answer 14

b) oily spaghetti

Question 15

T/F: membrane proteins from the ER require a highly specialized process for nuclear import compared to soluble protein

Answer 15

False - membrane and soluble proteins are generally imported the same way, and both have nuclear localization signals.

Question 16

What happens when CREB binds to DNA?

Answer 16

Depends on whether the CREB has been phosphorylated by activated PKA. Phosphorylated CREB has an activated transactivation domain that recruits CREB-binding protein (CBP). Inactive CREB binds to DNA, but does nothing.

Question 17

Simplest description of “activation of transactivation”

Answer 17

Phosphorylation of a protein leads to binds to other transcription factors.