exam 2 lecture 11

Question 1

mechanism for ligand-gated ion channel

Answer 1

first messenger ligand binds to channel function, channel opens to allow Na+, K+, Ca2+ to cross

Question 2

the 2 domains in the channels and what they are

Answer 2

extracellular- bind to the first messenger ligand
transmembrane- the pore for ions to flow

Question 3

mechanism for neural signaling through channels

Answer 3

neurotransmitter ligands released from excited presynaptic neuron into synaptic cleft, then binds to channel induced ion flow to cause postsynaptic siganl

Question 4

first messenger examples

Answer 4

serotonin, GABA, nicotine, acetylcholine, glutamate, glycine

Question 5

clinical relevance of ligand gated ion channels

Answer 5

involved in blood pressure regulation and cardiovascular disease

Question 6

ligand gated ion channel example

Answer 6

nicotine acetylcholine receptor

Question 7

mechanism for nicotine acetylcholine receptors

Answer 7

ace binds to extracellular LBD and causes channel to widen from 3-8 angstroms to have sodium flow and depolarize post-synaptic membrane

Question 8

receptor tyrosine kinases are what type of receptors

Answer 8

enzyme linked

Question 9

receptor tyrosine kinases mechanism

Answer 9

ligand binds and induced dimerization to active catalytic activity

Question 10

the activated cytoplasmic domains on the receptor tyrosine kinases do what to form binding sites

Answer 10

they autophosphorylate, the phosphorylate themselves onto tyrosine

Question 11

what are some examples of receptor tyrosine kinases

Answer 11

insulin, growth factor receptors

Question 12

how do receptor tyrosine kinases terminate signaling

Answer 12

receptor internalization- the ligand dissociated and leads to the dimer going back to single form

Question 13

what does dysfunction of receptor tyrosine kinases cause

Answer 13

cancer

Question 14

besides receptor internalization, another way to terminate the signaling from receptor tyrosine kinases could be

Answer 14

protein phosphatase as part of a protein phosphorylation cycle

Question 15

growth factor receptors bind what and initiate what

Answer 15

binds growth factor ligands and initiates the mitogen-activated protein kinase (MAP) cascade

Question 16

mechanism of MAP kinase cascade

Answer 16

growth factor binds and phosphorylates activating Ras protein, then GTP Ras activates MAP3K which triggers cascade

Question 17

Ras mutations lead to what

Answer 17

cancer

Question 18

what are the 3 Ras genes

Answer 18

HRas, KRas, NRas

Question 19

what are the two parts of the Ras structure

Answer 19

hypervariable region-localized at membrane
Gdomains

Question 20

what are the subunits of the G domain in KRas

Answer 20

switch 1, switch 2, p-loop (mutation spot)

Question 21

KRas is active and inactive when

Answer 21

active when GTP bound
inactive when GDP bound

Question 22

Ras is activated how

Answer 22

by growth factors binding to RTK or by cell receptors

Question 23

T/F Ras binds SPECIFIC effectors and activates MULTIPLE pathways

Answer 23

TRUE

Question 24

Guanine nucleotide exchange factors (GEFs) do what

Answer 24

increase rate of GDP dissociation and slow hydrolysis to promote cancer

Question 25

what proteins hydrolyze activated Ras

Answer 25

GTPase-activating proteins GAPs

Question 26

KRas mutation effects

Answer 26

decrease GTPase activity, increased affinity for GTP, KRas always active

Question 27

G-protein-coupled-receptors (GPCRs) have how many regions

Answer 27

7 alpha helical transmembrane regions

Question 28

GPCRs signal through what

Answer 28

heterotrimeric G-proteins

Question 29

T/F transient association with an agonist bound GPCR increases GDP release from Galpha

Answer 29

True

Question 30

Which subunit of trimeric G protein should be similar in structure to the monomeric G protein

Answer 30

G alpha

Question 31

what are the three subunits of heterotrimeric GPCRs

Answer 31

G alpha, G beta, G gamma

Question 32

which subunit has GTPase activity

Answer 32

G alpha