Cell Signaling

Question 1

Neuromuscular junction neurotransmitter

Answer 1

Acetylcholine

Question 2

Amino acid neurotransmitters

Answer 2

glycine, glutamate, asparate, GABA

Question 3

Monoamine neurotransmitters

Answer 3

epinephrine, norepinephrine, dopamine, serotonin

Question 4

Neuropeptide neurotransmitter

Answer 4

endorphins (some function as hormones)

Question 5

One neurotransmitter can bind to ____ receptors. What does this do?

Answer 5

multiple; elicits different responses based on that receptor

Question 6

direct neurotransmission

Answer 6

when a receptor binds to neurotransmitters causes ion channels to open

Question 7

Some transmitters cause depolarization of the post-synaptic cell

Answer 7

excitatory synapse

Question 8

Some transmitters cause hyperpolarization of the post-synaptic cell

Answer 8

inhibitory synapse

Question 9

Neurotransmission through G-protein-coupled receptors still results in ion channels opening on the plasma membrane (direct or indirect?)

Answer 9

Indirect

Question 10

Peptide hormones (hydrophilic)

Answer 10

cannot enter the cell –> hormone receptor binding activates G protein –> 2nd messenger cAMP produced

Question 11

“metabolic reaction”

Answer 11

target cells function

Question 12

G-protein-coupled receptor

Answer 12

extracellular ligand binding domain when BOUND –> intracellular domain (GEF activity domain) ACTIVATES G-PROTEIN –> can attach to adenylyl cyclase

Question 13

GEF

Answer 13

GDP + Pi —> GTP (active)

Question 14

GAP

Answer 14

GTP hydrolyzed back to GDP + Pi (inactive)

Question 15

cAMP (signal amplification) relative speed?

Answer 15

very fast (compared to hydrophobic ligand signaling on last exam)

Question 16

Adenylyl cyclase

Answer 16

inactive until activated by the activated G protein bound to GTP

Question 17

cAMP acts as a “messenger” to relay a message from ____ the cell to ____ the cell.

Answer 17

outside; inside

Question 18

1st messenger (the orig. chemical messenger) is ___ the cell.

Answer 18

outside

Question 19

2nd messenger (cAMP) and effector molecules that will bring about the desired response are ____ the cell.

Answer 19

within/inside

Question 20

Signaling through G-protein-coupled receptors can effect ______ ______.

Answer 20

gene expression

Question 21

Kinase (important enzyme in cell signaling)

Answer 21

adds a phosphate group = phosphorylates
- phosphorylation “activates” a protein

Question 22

Phosphatase (important enzyme in cell signaling)

Answer 22

removes a phosphate group = dephosphorylates
- “inactivates” a protein

Question 23

Most common phosphorylation targets (amino acid residue on a protein that is modified by addition of a phosphate group)

Answer 23

Serine, Threonine, Tyrosine, hydroxyl side chains

Question 24

Some cell surface receptors act as ______ _____ !!

Answer 24

intracellular enzymes

• some directly linked to intracellular enzymes

Question 25

Receptor tyrosine kinases

Answer 25

- largest family - phosphorylate substrate proteins on tyrosine residues

Question 26

Non-receptor tyrosine kinases

Answer 26

- not kinases but act like them by stimulating intracellular tyrosine kinases

Question 27

Receptor tyrosine kinase structure

Answer 27

- Ligand binding domain in (extracellular space) - Tyrosine kinase domain on (cytosolic side)

Question 28

Most ligands (to ligand binding domains of receptor tyrosine kinase structure) are _______ (growth factors)

Answer 28

Proteins

Question 29

Secreted peptides or hormones that bind to receptor tyrosine kinases (animal cells cannot grow without this)

Answer 29

Growth Factors

Question 30

Growth factors

Answer 30

- peptides can control specific target cells - involved in embryonic development - in adults, involved in growth/differentiation & immune cell proliferation

Question 31

what are the three big steps in receptor tyrosine kinases ligand binding?

Answer 31

1) monomer form of receptor is inactive 2) upon ligand binding, receptor becomes a dimer 3) In receptor-dimer, active sites of tyrosine kinase locate close to each other = autophosphorylation

Question 32

What steps follow phosphorylation of the receptor dimer?

Answer 32

1) phosphorylated receptor binds and activated "downstream signaling molecule"

Question 33

Receptor Tyrosine Kinases

Answer 33

Ras activation proteins (MAPK signaling), Pl3 kinase, phospholipase C (PLC-y) **These proteins have phosphorylation-tyrosine binding sites (SH2 domain)***

Question 34

Activated Ras protein

Answer 34

--> Activates MAP kinase cascade --> leads to activation of Cdks (cyclin-dependent protein kinases)

Question 35

Activated Phosphatidyl inositol 3 kinase (PI3)

Answer 35

--> adds a phosphate to 3-OH of any inositol phospholipid --> activates protein kinase B

Question 36

Activated Phospholipase C (PLC)

Answer 36

IP3 and DAG are produced --> leads to Ca2+ efflux from endoplasmic reticulum & PKC activation

Question 37

What does is mean when we say MAP kinase pathways signal in parallel in a cell?

Answer 37

In a single cell, multiple MAP signaling pathways can be activated simultaneously...each responding to different stimuli and potentially leading to separate cellular responses, all happening at the same time

Question 38

PI3 kinase pathway surppresses ___ and promotes _____.

Answer 38

apoptosis; cell survival

Question 39

Akt (PI3 pathway) INACTIVATES FOXO transcriptional activator. What does FOXO expression do??

Answer 39

Foxo expression = cell death (apoptosis); cell cycle arrest

Question 40

Akt ----| FOXO expression = cell ____; cell cycle ____

Answer 40

survives; proceeds - Activated Akt phosphorylates FOXO to inactivate its activity = cell survives and grows

Question 41

Receptor Tyrosine Kinase activates Phospholipase C (PLC) ---> ?

Answer 41

PLC catalyzes PIP2 breakdown

Question 42

What does PIP2 breakdown into?

Answer 42

IP3 and DAG

Question 43

What does IP3 and DAG production result in?

Answer 43

DAG bound to Protein kinase C (PKC) --> cell cycle regulation IP3 binds to receptor --> Ca2++ efflux from endoplasmic reticulum

Question 44

Non-Receptor Tyrosine Kinases

Answer 44

- JAK/STAT signaling - FAK--Integrin signaling

Question 45

Non-receptor tyrosine kinases ___ (do/do not) have intrinsic enzymatic activity

Answer 45

DO NOT; are associated with intracellular kinases & stimulate their activity

Question 46

Janus kinases (JAKs) associate with which receptors?

Answer 46

Cytokine receptors

Question 47

What proteins are key targets of JAK kinases?

Answer 47

STAT proteins

Question 48

Integrin initiates signaling for ______.

Answer 48

cell movement, proliferation

Question 49

what is a SH2 domain?

Answer 49

a protein molecule that binds to tyrosine-phosphorylated sequences in other proteins - linking receptor activation to downstream signaling

Question 50

What do receptor tyrosine kinases and non-receptor tyrosine kinases have in common?

Answer 50

?

Question 51

How are they different? (receptor tyrosine kinases and non-receptor tyrosine kinases)

Answer 51

?

Question 52

Receptors coupled to transcription factors

Answer 52

TGF-β NF-κB Wnt Notch