L7 Receptors Flashcards
Function of receptors
detect physical and chemical stimuli
Proteins embedded in plasma membrane detect
extracellular ligands
Transmembrane receptor function
transfer signal across plasma membrane
Intracellular receptors detect
permeable stimuli (gases, liquids)
No of receptor families in mammalian genome
25
What do members of each family share
one or more structurally homologous domains
Ion channels regulate
membrane potential
Effectors for ion channels
ions
Chemical signal generated by ion channels
change in ion composition of the cell
Ion channel key features
pore selectivity, gating mechanism
Ion pore selectivity
defined by physical size of filter and amino acids lining pore
Gating mechanism
ligand or voltage
Function of +ve charges in amino acids
voltage sensitivity
p loops location
between two TMs
TM receptors
transmembrane receptors
p loops function
create highly selective filter
Ion channel structure
subunits come together with pore in center
Closely packed TMs function
gate that blocks ion passage
Voltage gated ion channel gating
gating controlled by voltage sensing domain
Voltage gated K channel Kv1 structure
4 subunits each with 6 TMs
Inactivation peptide function in Kv1
blocks open pore
Kv1 additional units
beta cytoplasmic subunits
Ligand gates ion channels gating
gated by intracellularly or extracellularly chemical stimuli
Example of pentameric extracellular ligand gated ion channel
5HT, GABA
Example of tetrameric extracellular ligand gated ion channel
NMDA
Example of trimeric extracellular ligand gated ion channel
P2XR
What channels control membrane excitability
Na+/K+ selective channels
Cl- selective channels effect on CM
hyperpolarise cells
Glutamate ligand gated ion channels structure
dimer of dimers, binding site in cleft
Glutamate ligand gated ion channel binding site location
extended N terminal
Model of binding for glutamate ligand gated ion channels
clamp shell model - conformational change opens pore
What contributes to diversity of glutamate receptors
multiple genes, alternative splicing and RNA editing
Excess stimulation of NMDA receptors causes
stroke - leads to neuron death
Main example of pentameric ligand gated ion channel
nicotinic receptor
Pentameric ligand gated ion channel permeability
Na+ and K+
Nicotinic receptor structure
5 subunits each with 4 TMs
Pentameric ligand gated ion channels binding site
in alpha subunit
Advantage of complexity of subunits in one ligand gated ion channel family
diversity, oppurtunity for drug targeting
Control of excitability and function of muscle and neurons
by voltage gated ion channels and ligand gated ion channels
Myasthenia gravis cause
autoimmune induced loss of muscle nAChR
What mutations cause epilepsy
gain of function ion channel mutations
What does glutamate receptor signalling regulate
LTP required for memory formation
