Essential Pharmacology Pt1 Receptors Flashcards
Why is intercellular communication important?
cells need to communicate to co ordinate complex activities
Describe intercellular communication?
chemical signal that could be neurotransmitter or hormone is released from one cell
binds to specific receptors on specific cells and and produces a response
Why are receptor subtypes important?
Different receptor subtypes can evoke different responses in different cells
What are examples of the response brought about after receptor binding?
Secretory activity
Contractile activity
Metabolism
Membrane permeability
Rate of proliferation or differentiation
Lipid soluble signalling molecule?
can diffuse through phospholipid bi layer membrane
can bind to its receptor in cytosol or nucleus
Describe nitric oxide as a signalling molecule?
Binds to soluble guanylyl cyclase in the cytosol
Generates cGMP as 2nd messenger that regulates cell activity
Describe steroid hormone as signalling molecule?
Receptor is often a transcription factor that regulates transcription in the nucleus
Hydrophillic signalling molecule?
have to bind to receptors on cell surface
What are the different types of surface cell receptors for hydrophillic signalling mols?
receptor channels - ionotropic receptors
G protein-coupled receptors- metabotropic receptors
Receptor enzymes- receptors with intrinsic enzyme activity or bound to an enzyme
Integrin receptors- receptors that interact with cytoskeleton
Describe G protein- coupled receptors
biggest class of cell surface receptors
different g proteins couple to different 2nd messenger systems
G protein itself made up of three different subunits
may couple direct to ion channels
slow IPSPs or slow EPSPs
G protein coupled receptor can also be coupled to a different G protein that regulates an enzyme
What happens when signalling molecule binds to G protein coupled receptor?
when signalling molecule binds, activates the G protein and one of the subunits breaks off and the can go off and interact with other things.
Describe coupling of G protein to adenylyl cyclase?
When adenylyl cyclase is activated, breaks down ATP and generates cAMP as second messenger
CAMP regulates activity of protein kinase a
protein kinase a is going to go off and phosphorylate a specific residue on specific target protein and changes their acitivity
Describe coupling of g protein to phospholipase c?
Produces two second messengers ( IP3 and DAG)
IP3 releases calcium from stores in the endoplasmic reticulum
Calcium can then go on to regulate the activity of calcium dependent enzymes
Second second messenger is DAG and this regulates protein kinase C. protein kinase c is going to go off and phosphorylate a specific residue on specific target protein and changes their activity. Protein kinase c is calcium dependent
Where are the sources of calcium?
From internal stores via IP3- or Ca2+-stimulated release Ca2+ from endoplasmic reticulum
From outside the cell via voltage-gated or ligand-gated Ca2+ channels
Via inhibition of Ca2+ transport out of the cell
