Indirect Synaptic Transmission and Second Messengers Flashcards
(19 cards)
What is direct synaptic transmission?
transmitter binds directly to channel and opens the channel
What is indirect synaptic transmission?
transmitter binds to a receptor which itself is not a channel, but modulates the activity of ion channels
What are the subgroups of indirect synaptic transmission?
Activity of ion channels is modulated by:
A) direct modulation of channel function by G proteins
B) G protein activation of second messenger systems
How long do direct synaptic transmission take? Indirect?
1-4 msec; milliseconds to years
How many times do GPCR span the membrane?
7 times
What GPCR domain do glutamate and GABA bind to?
N-terminal domain
What GPCR domain do serotonin, dopamine, and noradrenalin bind to?
transmembrane domain
What are activators for GPCR?
- neurotransmitters
- light
- odorants
- tastants
Describe G protein structure
It is a trimer bade up from alpha, beta, and gamma subunits.
What are the different classes of G proteins?
stimulating and inhibiting
What are G-protein tools?
Cholera toxin and pertussis toxin
What is cholera toxin?
It is a cholerae toxin that stimulates G protein causing irreversible activation and opening of ion channels
What is pertussis toxin
It is a Bordetella pertussis toxin. It causes irreversible inactivation of inhibiting G proteins
Describe G protein cycle
- Metabotropic receptors bind to heterotrimeric G proteins
- GDP/GTP exchange release alpha and beta gamma subunit
- activate ion channels or second messenger signaling cascades
- intrinsic GTPase activity of alpha subunit results in reassociation of subunits
What ion channels are activated by G proteins?
K, Na, Ca
T/F: The beta gamma complex has a large range of action
False
How does norepinephrine regulate its own transmitter release?
negative feedback mechanism; alpha2 adrenergic receptor that is located on the presynaptic membrane
What is the advantage of using second messenger systems?
effects are more widespread
How are voltage-activated calcium channels activated?
- Norepinephrine binds beta-adrenergic receptor
- Sends off G protein
- G protein binds adenylate cyclase
- adenylate cyclase produce cAMP from ATP
- cAMP targets PKA
- PKA phosphorylates voltage-activated calcium channel
