Signal Transduction 3

Question 1

receptors basic categories

Answer 1

1-Ligand gated channels
2-Plasma membrane receptors
—-linked to g proteins
—-linked to protein kinase
3-Nuclear protein

Question 2

linked to protein kinase (plasma membrane)

Answer 2

RTK–Receptor Tyrosine Kinases

Question 3

GPCR regulate

Answer 3

Shorter term metabolic changes

Question 4

RTK regulate

Answer 4

differentiation, cell division, survival

Question 5

signal that stimulate dividing cells is

Answer 5

growth factor

Question 6

many growth factor share a common theme

Answer 6

1-growth factor binding result in dimerization of receptors
2-trans-auto-phosphorylate of cytoplasmic domain does not phosphorylate itself, phosphorylate the neighbor
3-cytoplasmic signalling activated by binding to phosphorylated tyrosine

Question 7

cytoplasimic signalling molecules associate with receptors by

Answer 7

SH2 and PTB domains

Question 8

SH2

Answer 8

amino acids chains contain binding pocket that interact with pTyr

Question 9

Adaptors

Answer 9

act as linkers enabling
contain SH2/PTB domain
Additional protein-protein interaction

Question 10

Adaptors with SH2 domain

Answer 10

GRB2 bind to RTK
SH3 domain associated with Sos

Question 11

Adaptor with PTB domain

Answer 11

IRS bind with RTK
lead to phosphorylation of IRS tyrosine
pTyr act as scaffolding for SH@ enzymes

Question 12

Effectors

Answer 12

1- STAT family
2- Signalling enzymes with SH2 Domains wich can directly bind to RTK

Question 13

STAT family

Answer 13

SH2 domain STAT bind to RTK, phosphrylate tyrosine in STAT, allow STAT dmierize, forming functional tanscription factor, trnaslocate to nucleus

Question 14

signalling enzyme (with Sh2 doamin and ability to bind with RTK

Answer 14

protein kinases
shp2
plc
GAPs

Question 15

signalling enzyme mechanism

Answer 15

1- recruitment of enzyme
2-binding of pTyr can result in conformational changes in catalytic domain
3- phosphorylation of enzyme can increase/decrease catalytic activity

Question 16

Termination

Answer 16

RTK doesn’t require Arrestin (GPCR need arrestin)
they have short motif interacting with AP2

Question 17

After binding with AP2: (3outcomes)

Answer 17

1- can resume within endosome
2- traficked by lysosome for degradation
3- returned to cell surface RE-sensitization

Question 18

G protein act as —- and —- to regulate cellular events

Answer 18

switches and timers

Question 19

Ras

Answer 19

small monomeric G protein s

Question 20

accessory protein help switch ras on/off

Answer 20

GAP: GTP hydrolysis
GDI: inhibitor–GDP can’t reactivate
GEF: activate GDP to GTP

Question 21

activated G protein is —- based

Answer 21

time

Question 22

RAs-MAP

Answer 22

1-EGF to RTK extracellular domain
2-dimerize
3- trans auto phosphorylate
4- GRB2 high affinity for pTyr
5-GRB2 assocaite with Sos
6-Sos is RasGEF
7- binding GRB2 to pTyr, brings Sos near Ras, allowing GDP to be replaced by GTP
8- Ras-GTP has high affinity for MAPKKK
9- MAPKKK phosphrylate Serine and Threonine in MAPKK
10- MAPKK phosphorylate MAPK
11- Activated MAPK can phosphorylate over 160 proteins
12- Activate genes in cell proliferation

Question 23

multiple pathways can be activated at the same time

Answer 23

Diverngence

Question 24

RAS when in active state should be inactivate to —-

Answer 24

avoid constitutional stimulation

Question 25

RAS inactivate by

Answer 25

RasGAP

Question 26

Ras extra mutation can lead to

Answer 26

cancer

Question 27

different members of MAP kinase family can elicit different cellular pathways via

Answer 27

having different MAPKKK/MAPKK/MAPK activate

Question 28

how many different MAP family we have

Answer 28

14 MAPKKK 7 mAPKK 13MAPK

Question 29

In signal transduction, linear pathway does not happen instead there is

Answer 29

conergence/divegence

Question 30

Nuclear Receptors

Answer 30

Soluble protein that mediate action of steroid hormones --lipid signaling molecule which can pass easily through plasma membrane ----receptor itself is an effector(no cascade)

Question 31

Nuclear receptors have two main domain

Answer 31

1- LIganid binding domain 2- DNA binding domain

Question 32

steroid receptors act by binding

Answer 32

HRE (hormone response element)

Question 33

Binding to HRE can be

Answer 33

enhanced or repressed gene expression

Question 34

DNA binding doamin is

Answer 34

two zinc-finger motifs

Question 35

starting material for synthesis steroid hormines

Answer 35

cholesterool

Question 36

cortisol is

Answer 36

glucocorticoids

Question 37

aldesterone is

Answer 37

mineralcorticoids

Question 38

corstisol pathway

Answer 38

1- enter the target cell 2- bind to glucocorticoid receptor 3-receptor changes conformation of the protein 4-expose nuclear localization signal 5- enter nucleus 6- activate/inhibit transcription

Question 39

Ligand gated channels

Answer 39

channel scan be opened/closed by binding of a ligand allow passage of specific ions ligand can be neurotransmitters

Question 40

Ligand gated activation

Answer 40

1-AP moves down a neuron to NMJ 2-AP opens voltage-gated Ca channels 3- elevated Ca conc. triggers ACh exocytosis 4-ACh will open ligand-gated Na channels 5- Na flows in 6- AP moves along membrane into t-tubules 7- AP activate voltage-gated CA channels on SR 8- Ca is released into cytoplasm and act as second messenger 9-Troponin C undergo conformational change 10- relieving tropomyosin blockage of actin-myosin binding site 11- myosin can now cause interaction **calcium-induced-clacium-released**