White: Cell signaling 1&2

Question 1

Adenylyl cyclase is an example of

Answer 1

An effector

Question 2

SOS is a _____ that binds _____

Answer 2

GEF, which binds and phosphorylates Ras (Small GTPase)

Question 3

MAP kinase cascade

Answer 3

MAP kinaseX3 (Raf) ---->
MAP kinaseX2 (Mek) ---->
MAP kinase (Erk)---->
Nucleus---->
Increased gene transcription---->
Uncontrolled cell division (cancer)

Question 4

Activated PKA can

Answer 4

Regulate proteins by addition of phosphate group
Phosphate group can form part of structure that other proteins recognize
Alter activation/inactivation of target proteins
Alter intracellular localization of proteins
Alter abundance of proteins

Question 5

GRKs– G-protein receptor kinase function

Answer 5

Phosphorylate receptor such that another protein -arrestin- binds to the 3rd loop of the receptor and prevents G-alpha from interacting with 3rd loop
Result is that G protein and G-alpha-GDP does not get converted to G-alpha-GTP by receptor

Question 6

G-protein subunits

Answer 6

Alpha, beta, gamma subunits

Question 7

Phospholipase C does what

Answer 7

Cleaves membrane protein PIP2

Question 8

Receptor destruction

Answer 8

Endosomes + lysosomes/proteases

Question 9

Hfe mutation

Answer 9

If Hfe is mutated it cannot associate with Tfr2 so Hepcidin expression cannot be increased
If Hepcidin can not be increased, ferroportin receptors will not be internalized and excess iron will flow into blood

Question 10

Grb2 has ______ domain that binds _____

Answer 10

SH3 domain of Grb binds to Prolines in SOS

Question 11

When iron is high, Hepcidin….

Answer 11

Hepcidin expression increases which lowers amount of ferroportins

Question 12

DMT1

Answer 12

Iron transporter - transports iron into intestinal cell

Question 13

Effects of DAG

Answer 13

DAG, along with calcium, bind PKC which phosphorylates a variety of membrane and cytoplasmic substrates

Question 14

PIP2 produces

Answer 14

DAG and IP3

Question 15

JAK-STAT pathway

Answer 15

Receptors bind ligand (cytokines)
Receptors dimerize and bind JAK
JAKs phosphorylate eachother and receptor
Receptor binds and phosphorylates STATs
STATs dissociate, dimerize, and go to nucleus
STATs bind DNA and cause transcription

Question 16

Hormone level drop

Answer 16

Decreased adenylyl cyclase activity - decreased cAMP - decreased PKA activity

Question 17

Remove signaling molecule

Answer 17

Phosphodiesterases will remove cAMP

Question 18

What effector is activated when GPCR (G-protein coupled receptor) binds Gaq or Gao

Answer 18

Phospholipase C

Question 19

Hereditary hemochromastosis causes

Answer 19

Uncontrollable iron absorption

Question 20

Effects of IP3

Answer 20

Triggers release of calcium from ER by binding to IP3 gated calcium channel
Calcium can act as second messenger

Question 21

RTKs bind to

Answer 21

SH2 domain on adaptor proteins (Grb2)

Question 22

2 major cell responses from external signals

Answer 22

Change in activity or function of enzymes/proteins in the cell- Fast
Change in amounts of proteins by change in gene expression- Slow

Question 23

Ferroportin

Answer 23

Iron transporter- transports iron out of intestinal cell and into blood

Question 24

Calcium function as second messenger

Answer 24

Binds/activates calmodulin

Calmodulin then activates other proteins such as CaM kinase II which can activate transcription factors

Question 25

Hfe

Answer 25

Membrane protein that binds to Tfr1
When iron binds Tfr1, Hfe is activated and binds Tfr2
Tfr2 then works through Smad pathway to induce Hepcidin expression

Question 26

Epinephrine induces

Answer 26

Activation of PKA

Question 27

cAMP is an example of

Answer 27

A second messenger

Question 28

Hepcidin

Answer 28

Regulator of iron homeostasis

Binds ferroportin and causes internalization/destruction

Question 29

JAK-STAT is a

Answer 29

More direct route for impacting transcription

Question 30

Nitric oxide signaling is an example of

Answer 30

Paracrine signaling

Question 31

Serine-Threonine receptor pathway

Answer 31

More direct route to impact transcription
Receptor activated by phosphorylation
Receptor binds R-Smad and phosphorylates
R-Smad binds Co-Smad and they move into nucleus to effect transcription

Question 32

Steps of G-protein signaling

Answer 32

Ligand binds receptor
Conformational change in receptor
Receptor binds G-protein
Receptor acts as GEF
G-alpha protein changes conformation-replaces GDP with GTP
G-alpha becomes active and binds effector molecule
Effector molecule is activated (i.e.-adenylyl cyclase activates and forms cAMP)

Question 33

Ras binds _____ and initiates

Answer 33

Raf, initiates MAP kinase cascade

Question 34

Types of receptors

Answer 34

Transmembrane and intracellular

Hydrophobic molecules can cross membrane and bind intracellular receptors

Question 35

RTK Receptor tyrosine kinase description

Answer 35

Important role in signal transduction
Enzyme linked receptors
Used for response to growth factors
Autophosphorylates

Question 36

cAMP activates, it takes how many molecules of cAMP

Answer 36

Protein kinase PKA

2 cAMP molecules required to activate

Question 37

Intracellular receptors effect what when activated

Answer 37

Typically effect gene expression

Question 38

Erythropoeitin and JAK-STAT

Answer 38

Erythropoeitin employs JAK-STAT to initiate signaling

Question 39

Receptor sequestration

Answer 39

Endosomal invagination of area of membrane w/receptor

Question 40

Densensitization

Answer 40

Ability to turn off or reject signal

Question 41

Downstream effects of PKA in fight/flight response

Answer 41

Generate lots of ATP
liver-break down glycogen to glucose
liver-inhibit glycogen synthesis
Cardiac muscle- increase contraction
Adipose tissue- Hydrolysis of triglycerides to generate glucose