BI203 Lecture 21: Cell Signaling - Slides 85-97 (MAP Kinase Pathway and Signaling Networks)

Question 1

___ ___ pathway - A cascade of protein kinases that is highly conserved in evolution, found in all eukaryotic cells.

Answer 1

MAP Kinase pathway

Question 2

___ ___ are serine/threonine kinases.

Answer 2

MAP kinases

Question 3

MAP kinases were initially found in mammalian cells belonging to the ___ family.

Answer 3

ERK (extracellular signal-regulated kinase) family

Question 4

___ ___ ___ pathway - Key pathway regulating animal cell proliferation.

Answer 4

ERK MAP Kinase Pathway

Question 5

The role of ERK signaling emerged from studies of ___ proteins, first identified as the oncogenic proteins of viruses that cause sarcomas in rats.

Answer 5

Ras

Question 6

Ras is activated by ___ ___ ___ ___ (GEFs) that stimulate exchange of GDP for GTP.

Answer 6

Guanine nucleotide exchange factors (GEFs)

Question 7

Ras-GTP activity is terminated by GTP hydrolysis, stimulated by interaction of Ras-GTP with ___ ___ (GAPs).

Answer 7

GTPase-activating proteins (GAPs)

Question 8

Mutations in many human cancers keep Ras in an active ___ state

Answer 8

GTP-bound

Question 9

Autophosphorylation of ___ leads to binding of Ras GEFs (Activation of Ras).

Answer 9

RTKs

Question 10

Activation of Ras leads to activation of the ___ ___.

Answer 10

Raf kinase

Question 11

Raf kinase then phosphorylates and activates a second protein kinase ___.

Answer 11

MAP

Question 12

MAP then phosphorylates and activates the MAP kinase ___.

Answer 12

ERK (extracellular signal-regulated kinase)

Question 13

ERK phosphorylates a variety of proteins involved in cell ___.

Answer 13

proliferation

Question 14

Some activated ERK proteins go to the nucleus, where they regulate transcription factors by phosphorylation.

A primary response to growth factor stimulation is rapid transcription of ___ genes.

Answer 14

immediate-early genes

Question 15

Rapid transcription of immediate-early genes is mediated by a regulatory sequence called the ___ ___ ___ (SRE).

Answer 15

serum response element (SRE)

Question 16

The serum response element (SRE) is recognized by transcription factors including the ___ ___ ___ (SRF) and ___.

Answer 16

serum response factor (SRF), Elk-1

Question 17

Many immediate-early genes encode transcription factors.

Their induction leads to altered expression of a battery of other downstream genes called ___ ___ genes.

Answer 17

secondary response genes

Question 18

Specificity of MAP kinase signaling is maintained partly by physical association on ___ proteins.

Answer 18

scaffold proteins

Question 19

The four main pathways which can regulate cell proliferation and survival:

Answer 19

cAMP pathway, PI 3-kinase/Akt & mTOR pathways, MAP kinase pathways

Question 20

Activity of signaling pathways is controlled by ___ ___.

Answer 20

feedback loops

Question 21

___ is the interaction between signaling pathways.

Answer 21

crosstalk

Question 22

G protein-coupled receptors can be linked to MAP kinase signaling pathways by ___, which are scaffold proteins.

Answer 22

β-arrestins

Question 23

β-arrestin serves as a ___ protein for Raf-MEK-ERK signaling, linking this MAP kinase pathway to G protein-coupled receptors.

Answer 23

scaffold protein

Question 24

Multiple signaling pathways interact with one another to form ___ ___ within the cell.

Answer 24

signaling networks