BI203 Lecture 21: Cell Signaling - Slides 67-84 (PI 3-kinase/Akt Pathway)

Question 1

___ ___/___ pathway: Based on a secondary messenger derived from the membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2).

Answer 1

PI 3-kinase/Akt pathway

Question 2

PIP2 is phosphorylated by phosphatidylinositide (PI) 3-kinase to yield the secondary messenger ___.

Answer 2

PIP3

Question 3

PIP2 is phosphorylated by ___ ___ to yield the secondary messenger PIP3.

Answer 3

PI 3-kinase

Question 4

PIP2 and PIP3 are types of ___.

Answer 4

phospholipids

Question 5

PI 3-kinase is activated downstream of both ___ ___ receptors and ___ ___ ___.

Answer 5

G protein-coupled receptors, receptor tyrosine kinases

Question 6

Recruitment of PI 3-kinase to activated ___ stimulates PI 3-kinase activity.

Answer 6

RTKs

Question 7

PIP3 targets a serine/threonine kinase called ___ via its pleckstrin homology (PH) domain.

Answer 7

Akt

Question 8

Akt binds PIP3 via its ___ ___ domain.

Answer 8

pleckstrin homology (PH) domain

Question 9

Akt is phosphorylated at the plasma membrane by ___ and ___.

Answer 9

mTORC2, PDK1

Question 10

Once Akt is activated, it inactivates ___ - TFs that activate transcription of genes that inhibit cell proliferation & induce cell death.

Answer 10

FOXO

Question 11

When ___ ___ are present, Akt is activated, and it inactivates both FOXO and GSK-3.

Answer 11

growth factors

Question 12

An activated Akt also targets ___ = A protein-serine / threonine kinase that is inhibited by phosphorylation by Akt.

When active, ___ regulates numerous targets.

Answer 12

GSK-3

Question 13

PI 3-kinase/Akt/GSK-3 signaling pathway regulates global translation by phosphorylating ___ and ___.

Answer 13

eIF2, eIF2B

Question 14

___ of growth factors -> Global translation proceeds.

___ of growth factors -> Global translation inhibited due to phosphorylation of eIF2 and eIF2B.

Answer 14

presence, absence

Question 15

The ___ pathway also controls global translation by coupling protein synthesis to the availability of growth factors, nutrients, and energy.

Answer 15

mTOR pathway

Question 16

The ___ complex is activated downstream by Akt and regulates cell size by controlling protein synthesis.

Answer 16

mTORC1 complex

Question 17

The mTORC1 complex regulates global translation via phosphorylation of ___ ___.

Answer 17

eIF4E-binding protein (4E-BP)

Question 18

mTORC1 also inhibits protein degradation by regulating ___.

Answer 18

autophagy

Question 19

When cells are starved of nutrients, mTORC1 activity ___.

Answer 19

decreases