Indirect Synaptic Transmission and Second Messengers Flashcards
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
