6. Receptors in Cell Signalling & Principles of Receptors Mediators Endocytosis Flashcards
How do you classify and sub classify receptors?
Classified according to they agonist the recognise
Sub classified via looking at the affinity of different antagonists
What are the 3 classifications of chemical signals according to their function?
Hormones
Neurotransmitter
Local chemical mediators
Give 3 examples of classical ligand gated receptors
Nicotinic
GABA
Glycine receptors
What enzyme is commonly used on membrane bound receptors with integral enzyme activity?
Tyrosine kinase
What type of hormones can cross the cell membrane and bind to intracellular receptors?
Steroid hormones
Intracellular receptors in the resting state are stabilised by what proteins?
Heat shock
Chaperone
Name 2 cells with the ability to phagocytose?
Macrophages
Neutrophils
What is pinocytosis?
Invagination of the membrane to form a lipid vesicle
Explain the uptake of cholesterol
1 LDL binds to receptors that recognise apoprotein B (these are located above coated pits)
2 Membrane invaginate a to form coated vesicles (coats then removed)
3 Vesicles then fuse with endosomes
4 pH causes receptor to dissociate and recycle
5 LDL endosomes then fuse with lysosomes where cholesterol is released from esters
What is the structure of the coat on a coated vesicle?
Triskelions made of clathrin
Removal requires ATP and proteins
Name a receptor and ligand pair where both are degraded
Insulin
Growth factor
What happens to the receptor and ligand with transferrin?
Both ligand and receptor are recycled
What is glaucoma?
Abnormally raised intraocular pressure which untreated can lead to blindness
What are the two types of glaucoma?
Closed angle - Iris bunches over the drainage canals (acute emergency)
Open angle - drainage canals become blocked over time
What agonists can be used to treat glaucoma?
Alpha 2 agonists - decrease aqueous humour production and increase outflow
M3 agonists - act on the trabecular mesh work increasing outflow (pilocarparine)
