Tissues 11: Signalling between cells II Flashcards
What are ionotropic receptors
a
How do iontropic receptors function
A ligand binds to the receptor causing the ion permeable pore to open allowing molecules to traverse the membrane
What is a G-protein coupled receptor
a
What is an enzyme linked receptor
a
What is an intracellular receptor
a
What are the signal transduction events of an iontropic receptor
a
Give some examples of ionotropic receptors
Nicotinic Acetycholine receptor
Ligand: Acetylcholine(ACh)
Location: Skeletal muscle
Physiological effect: Muscle contraction
GABA(a)
Ligand: gamma-amino butyric acid(GABA)
Location: Neuronal
Physiological effect: Decrease neuronal excitability
How do G proteins work
7-TM receptor and heterotrimeric G-protein are inactive
Ligand binding on outside causes change conformation of receptor
Unassociated G-protein binds to receptor
GDP is exchanged for GTP
G-protein dissociates into two active components
alpha subunit
betagamma subunit
Each binds to their target proteins
(add photo)
Internal GTPAse activity on alpha subunit dephosphorylates GTP
alpha subunit dissociayes from target protein
What is a hetertrimeric protein
a
What does 7-TM stand for
a
Which subunits stay together in a heterotrimer
a
How many main isoforms are there of the G alpha subunit
3
What are the 3 G alpha subunits and what are the differences
G alpha s - stimulates adenylyl cyclase
G alpha i - inhibits adenylyl cyclase
G alpha q - stimulates phospholipase C
What does atropine do
a
What do G alpha s subunits do
a
What do G alpha i subunits do
a
What do G alpha q subunits do
a
Give examples and effects of Galpha subunits
a
Why are G protein coupled receptors so important
a
What is the generic mechanism of action for enzyme linked receptors
Ligand binding - receptor clustering
Receptor clustering activates enzyme activity within cytoplasmic domain
Enzymes phosphorylate receptor
a
Give some examples of enzyme-linked signal transduction
Insulin receptor (CD220 antigen)
Ligand: Insulin
Physiolgical effect: Glucose uptake
Enzyme: tyrosine kinase
ErbB receptors Ligand: Epidermal growth factor Transforming growth factor beta Physiological effect: Cell growth and Proliferation Enzyme: tyrosine kinase
Guanylyl-cyclase linked receptors
NPRA
Ligand: Atrial/Brain natiriuetic peptide
Physiological effects
a
Which processes are enzyme-linked signal transductions generally linked to
a
How many types of intracellular receptors are there
2
How do type I intracellular receptors work, where are they located and give their structure
Cytoplasmic
Located within cystolic compartment
Associated with chaperone molecules
(heat shock proteins, hsp)
Hormone binds to receptor - hsp dissociates
2 hormone bound receptors form a homodimer
The hormodimer translocates to the nucleus - binds to DNA
Produce an order in terms of time of which signalling is fastest and slowest and give reasons
a
How do type II intracellular receptors work, where are they located and give their sturcture
a
Give examples of type I intracellular receptors
Gluc
Give examples of type II intracellular receptors
a
