Synaptic Transmission

Front 1

2 major types of receptors

Back 1

ionotropic and metabotropic

Front 2

Define ionotropic receptors

Back 2

ligand gated ion channels

Front 3

Define metabotropic receptors

Back 3

ligand-induced second messenger generators that alter the "metabolism" of the cell

Front 4

which receptor has fast onset and termination

Back 4

ionotropic

Front 5

Which receptor shows amplification of response and diversity

Back 5

metabotropic

Front 6

are there transmitters that bind to both iono and metabotropic receptors

Back 6

yes, Ach, GABA, Glutamate

Front 7

Describe location of ionotropic and metabotropic receptors

Back 7

ionotropic are often located near transmitter release sites, metabotropic are usually not near transmitter release sites

Front 8

Name Ach ionotropic receptor

Back 8

nicotinic

Front 9

Name Ach metabotropic receptor

Back 9

muscarinic

Front 10

name model organism for study of nicotinic Ach receptors

Back 10

electric organ of Torpedo electric fish

Front 11

How many subunits are there in nAchR

Back 11

5 subunits - 2 alpha, beta, gamma and delta, all 5 subunits form staves on barrel arrangement

Front 12

Describe subunit of nAchR

Back 12

4 regions (M1-M4), M2 from each subunit forming lining of pore

Front 13

Which subunit has binding sites for transmitter

Back 13

alpha subunits

Front 14

What happens when Ach binds to receptor

Back 14

if only one Ach binds will have brief flickering, if 2 Ach bind will have normal opening

Front 15

Name toxins that block Ach binding

Back 15

alpha bungarotoxin/curare

Front 16

describe ion selectivity of Ach receptors

Back 16

multi ion selectivity - equally permeable to Na and K. some permeability to Ca, depends on alpha subunit 7

Front 17

what is the equilibrium potential of Ach receptor

Back 17

0 mV

Front 18

Name 2 classes of glutamate receptors

Back 18

NMDA and non NMDA

Front 19

What NMDA stands for

Back 19

N mmethyl D aspartate

Front 20

Describe NMDA receptor

Back 20

-activated by NMDA agonist
- high conductance (50 pS)
-permeable to Ca, Na, K
-pore is plugged by Mg at resting potential, plug is removed by depolarization
-relatively slow gating
-lots of modulatory sites (glycine, Zn, PCP)

Front 21

Name 2 classes of non NMDA receptors

Back 21

AMPA and kainate

Front 22

Describe non NMDA receptor

Back 22

-lower conductance (20 pS)
-permeable mostly to only Na and K
-fast gating

Front 23

what is the most common inhiitory NT

Back 23

GABA, inhibitory because does not conduct Na or K , but Cl, used by many interneurons

Front 24

Ionotropic GABA receptor is..

Back 24

ligand gated Cl channel

Front 25

Chloride is _ outside, _ inside

Back 25

high, low

Front 26

Equilibrium potential for Cl channel

Back 26

-70

Front 27

Pertussis toxin

Back 27

travels across cell membrane and inactivates galpha i protein and g alpha 0 , uncouples and prevents action of metabotropic receptor

Front 28

what happens if add NT and receptor is metabotropic

Back 28

will inhibit activity

Front 29

what effects which pathway you chose

Back 29

primary effector effects, not g protein or receptor

Front 30

Direct pathway

Back 30

g protein directly associates with final receptor

Front 31

what is most common direct pathway

Back 31

beta gamma

Front 32

How do you know beta gamma acts on K channel directly

Back 32

use reconstitution, overexpress K channels

Front 33

How many subunits does g protein have

Back 33

3 subunits - alpha beta gamma

Front 34

describe g protein in resting state

Back 34

all three subunits associate with each other and receptor, alpha subunit binds GDP (high affinity)

Front 35

what happens to g protein when NT binds

Back 35

it loses affinity for GDP, and binds GTP since its more abundant, alpha dissociates from beta and gamma

Front 36

How does alpha subunit inactivate

Back 36

it turns itself off since it is a slow GTPase, when GTP is cleaved back to GDP, complex reassociates and protein returns to active state

Front 37

what experiments can be done to prove GTP is used

Back 37

1) remove GTP
2)replace GTP with GTP gamma s which is non hydrolyzable form and will cause persistent activation
3)replace with GDP beta s which has high affinity binding to alpha subunit of g protein will causes block of signaling

Front 38

what determines diversity and specificity of actions

Back 38

1. specific g protein receptor interactions
2.use of either beta gamma or alpha subunits
3 diverse second messenger cascades

Front 39

Specific g protein receptor interactions

Back 39

there are 20 alpha, 5 beta 7 gamma subunits, allows number of combinations

Front 40

Describe antisense oligonucleotides experiment

Back 40

inject into cells sequence of about 20-30 amino acids that is complimentary to MRNA that codes for g protein. When bound, mRNA will be double stranded and will not be translated into protein, after time protein will be depleted

Front 41

Both somatostatin and Ach reduce Ca, is it same g protein

Back 41

no, uses different alpha, beta and gamma subunits, this may reduce crosstalk , allows for specificity

Front 42

Receptor signaling compartmentalization

Back 42

receptor , g proteins and interacting proteins are all within different compartments of the cell

Front 43

General scheme of messenger action

Back 43

First messenger-->receptor-->transducer-->primary effector-->second messenger--> secondary effector

Front 44

what does activation of muscarinic receptors do in heart cells

Back 44

opens K+ channels causing hyperpolarization and decreasing heart rate

Front 45

How do you do reconstitution

Back 45

inject oocyte with GIRK channels and g protein subunits

Front 46

what happens when you express beta gamma RNA with GIRK channel but exclude GTP

Back 46

doesnt block beta gamma effect

Front 47

same but add GDP beta s

Back 47

doesnt block beta gamma effect