Unit III Week 3

Question 1

Microtubule structure and function

Answer 1

tubular, 25 nm diameter
tubulin (a and ß)
movement (cilia/flag and organelles), scaffold
cell division

Question 2

Microtubule accessory proteins and nucleotide

Answer 2

motor proteins: kinesin and dynein

GTP for growth

Question 3

Microfilament (actin filament) structure and function

Answer 3

helical filament 5-9 nm diameter
actin
cell movement, contraction

Question 4

Intermediate filament structure and function

Answer 4

staggered tetramer of c-c dimers, 10 nm diameter
keratin, vimentin, neurofilaments, nuclear lamins
mechanical stability

Question 5

Intermediate filament accessory proteins

Answer 5

crosslinking, membrane anchor

Question 6

Microtubule dynamics/regulation

Answer 6

GTP cap, GDP in base
Severing proteins: katanin, spastin, fidgetin, VPS4
All ATPases (NSF like) which pull on C’ end sticking out
Disease: hereditary spastic paraplesia

Question 7

Microfilament (actin filament) formation

Answer 7

1. G-actin concentration (profilin)
2. ADP to ATP exchange (profilin)
3. Capping (gelsolin)
4. Depolymerization/severing (ADF/cofilin)

Question 8

Microfilament (actin filament) nucleation

Answer 8

1. FH2 nucleation mimic actin and bind two more (bundle)
2. Arp2/3 complex with WASP and binds one more (branch)
   Both paths activates by GTPase (Ras, Rho, Rac etc)

Question 9

Actin filaments _____ at + end and ______ at - end

Answer 9

grow

shrink

Question 10

Examples of asymetric cell division

Answer 10

erythroblast (eject nucleus)
platelets (polypliod megakaryocyte)
spermatogonia (long chain of almost pinched)
epithelial cells (apical side larger)

Question 11

Regulation of actomyosin ring

Answer 11

Rho activated by high conc. microtubules (only middle)
RhoGDP - RhoGTP cycle (phos by Ect2)
RhoGTP activates ROCK
ROCK activates myosin

Question 12

Types of communication between cells

Answer 12

Paracrine/autocrine
Endocrine
Contact dependent
Synaptic

Question 13

Types of signaling molecules

Answer 13

Lipophilic: steroids, no vesicles, slow
Hydrophilic: peptide, vesicles, fast

Question 14

Types of signal termination

Answer 14

Constitutively active terminators (PDEs)
Signal induced terminators (GAP enhanced GTPase)
Negative feedback mechanism terminators (Ca2+ pumps)

Question 15

PDE5

Answer 15

Converts cGMP to GMP
two binding site (cooperative binding)
Targeted by drug Sildenafil (continued Ca2+ release, smooth muscle relaxation)

Question 16

Neworks and pathways: nodes

Answer 16

multiple inputs and/or outputs

Question 17

Tyrosine kinase activation

Answer 17

Ligand binding drives dimerization (homo or hetero)

Results in cross phosphorylation and activation

Question 18

RasGTP regulation

Answer 18

RasGTP = active
GAP - activates hydrolysis ->RasGDP
GEF - exchanges GDP -> RasGTP

Question 19

Ras activation example

Answer 19

Receptor dimer binds Grb2 (adaptor protein)
Sos binds Grb2 (GEF) (critical step, need Sos near PM)
PROXIMITY
Grb2 (GEF) results in RasGTP activation

Question 20

Two classes of blocking tyrosine kinase

Answer 20

Antibodies - block ligand biding to receptor

Tyrosine kinase inhibitors - bind substrate site on kinase

Question 21

EGFR role in some cancers

Answer 21

Overexpressed
Increased EGFR = poorer clinical outcome
Stimulates more ligand (autocrine signaling)

Question 22

Response to EGFR targeted therapy

Answer 22

Depends on amount of EGFR expression in cancer

Determine by FISH/IHC

Question 23

Resistance to tyrosine kinase inhibition

Answer 23

Primary resistance: mutation is further down pathway

Secondary resistance: new mutation in receptor blocks inhibitor, or activation of other receptors with same effect

Question 24

ß1-AR pathway

Answer 24

Sympathetic, NE binds
Gs(a) activates AC, ATP->cAMP, PKA, Ca2+ channels
Cardiac muscle contraction

Question 25

a1-AR pathway

Answer 25

Sympathetic, NE binds Gq(a) activates PLC, PIP2->IP3 and DAG DAG, PKC, L-Ch (and IP3) Ca2+ release Peripheral vasoconstriction (increase return, BP)

Question 26

propanolol, metoprolol

Answer 26

beta-blockers | decrease heart rate and blood pressure

Question 27

prazosin

Answer 27

alpha-blocker | decrease blood pressure

Question 28

m2-MR pathway

Answer 28

Parasympathetic, acetylcholine Gi(a) activates and inactivates AC (from Gs(a)/ß1-AR) Still need PDE to convert existing cAMP to AMP ßy binds GIRK and opens K+ (decreases excitability in heart)

Question 29

ß2-AR pathway

Answer 29

Sympathetic, NE binds Gs(a) activates AC, ATP->cAMP, PKA, Ca2+ channels Smooth muscle relaxation - bronchodilation

Question 30

m3-MR pathway

Answer 30

Sympathetic, NE binds Gq(a) activates PLC, PIP2->IP3 and DAG DAG, PKC, L-Ch (and IP3) Ca2+ release Bronchoconstriction

Question 31

ipratropium inhalation (m3-MR antagonist)

Answer 31

inhibit bronchoconstriction

Question 32

albuterol (ß2-AR agonist)

Answer 32

support bronchodilation

Question 33

GRK kinase

Answer 33

binds ßy (independent of a) and phosphorylates receptor ß-arrestin binds phos-GPCR Desensitization and re-integration or degradation

Question 34

Humans have _____ kinases and _____ phosphatases

Answer 34

518, 130

Question 35

Structure of ATP

Answer 35

Purine base Ribose sugar Phosphates with PAH bonds (phosphate donor) Can be converted to 2nd messenger

Question 36

Conserved structure of kinases

Answer 36

``` beta sheet group alpha helix group helix C activation loop (phosphorylated when in correct position, not all kinases have this) action happens between groups ```

Question 37

Open/close movement of kinases

Answer 37

Both needed for activity | Different position of glycine loop

Question 38

Differences in kinases for drug development

Answer 38

More differences in inactive state (2 of 4) 1. activation loop 2. c helix 3. glycine rich loop 4. ATP binding pocket

Question 39

MAP kinase pathway

Answer 39

Input, MAPKKK, MAPKK, MAPK, ouput | (eg glycerol synthesis or IL-2)

Question 40

IL-2 pathway (MAP kinase contribution)

Answer 40

T-cell receptor, RasGTP pathway, Raf-1 (MAPKKK), MEK (MAPKK), erk (MAPK), NFATn Still need NFATc

Question 41

IL-2 pathway (Calcineurin contribution)

Answer 41

T-cell receptor, PIP2 to DAG (PKC), IP3, increase Ca2+ Inhibit calcineurin, stop phosphorylating NFATc NFATc enter and binds with NFATn IL-2

Question 42

IL-2 T-cell proliferation pathway

Answer 42

IL-2 binds T-cell, mTOR/Cdk2 = proliferation

Question 43

Excitatory CNS synapse

Answer 43

AMPA-R (glutamate receptor) opens, Na+ in Opens NMDA-R, eject Mg2+, Ca2+ in Stimulates AMPA-R proliferation POTENTIATION (positive feedback)

Question 44

Sources of androgen in body

Answer 44

Testis Adrenal glands Intracrine (in prostate cells)

Question 45

Androgen receptor structure

Answer 45

N' transactivation domain DNA binding domain Hinge region C' ligand binding

Question 46

Androgen receptor function

Answer 46

in cytoplasm binds ligands and disassociates chaperones enters nucleus, homodimerizes, binds DNA recruits coactivators and gene expresson

Question 47

Mechanisms of resistance to traditional prostate cancer therapies

Answer 47

AR activation via non-testis androgen Overexpression of AR AR mutation (gain of function) Truncated AR with constitutively active LBD

Question 48

Abiraterone

Answer 48

inhibits CYP 17 (androgen formation) Side effects: hypokalemia, edema, hypertension due to excess mineralcoracoids

Question 49

Enzalutamide

Answer 49

antiandrogen | inhibits binding of T to AR (inhibits downstream)