Lecture 5: Metabotropic Receptors Flashcards
How do heterotrimeric G-protein receptors work?
ligand binds to the receptor -> receptor interacts with heterotrimeric G-protein -> heterotrimeric G-protein dissociates and alters the function of different intracellular signalling pathways which produces changes in ion conductance
What is the structure of a GPCR?
seven transmembrane spanning l domains
What are the three main types of G protein?
Ga/Gas, Gai and Gaq
How do metabotropic receptors alter neuronal activity?
via intermediate steps between receptor and ion channels
What do different G-protein effectors produce?
different second messengers
What are the different ways metabotropic receptors act presynaptically?
presynaptic facilitation
presynaptic inhibition
How can changes in Ca2+ alter neuronal function?
via gene expression
How do metabotropic transmitter systems modulate postsynaptic neuronal membrane potential?
via second messenger pathways
Why do metabotropic receptors act presynaptically?
to modulate neurotransmitter release
What can second messengers derived from activation of metabotropic receptors alter?
neuronal gene expression
How is noradrenaline and adrenaline synthesised?
tyrosine is converted by tyrosine hydroxylase to DOPA
DOPA is converted by DOPA decarboxylase to dopamine
dopamine is converted by dopamine β hydroxylase to noradrenaline
noradrenaline is converted by phenylethanolamine-N-methyl-transferase to adrenaline
How is a neuron’s neurochemical phenotype determined?
by the presence of certain enzymes
What does calcium influx stimulate?
production of monoamines
Where is DBH and PNMT present?
within vesicles
Which enzymes are involved in the breakdown of monoamines?
monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT)
