What is a receptor?
Responds to stimuli and generates a response
How does the same receptor compare in different cells?
The same receptor may produce different responses in different cells
How do receptor sub types compare in the same cell?
May provide different responses
How to receptors allow specificity?
By only binding to certain substrate
What things could a receptor alter as part of the response?
Rate of proliferation or differentiation
What is the process of a receptor binding to a substrate and producing a response known as?
Signal transduction, or cell signalling
What is signal transduction (cell signalling)?
Transmission of a molecular signal from a cells exterior to its interior
What are the 3 main examples of receptors?
Plasma membrane receptor
G protein coupled receptor
What must lipids that bind to intracellular receptors be and why?
Lipophillic as they need to pass through the cell membrane
What are two common intracellular receptor substances?
What happens when steroid hormones bind to intracellular receptors?
Binds to receptor
Often transcription factor, altering rate
What does nitric acid do when it binds to an intracellular receptor?
Binds to soluble guonylyl cyclose
Generates cGMP as a second messenger which regulates cell activity
What kind of receptor do molecules that cannot penetrate the cell membrane need to combine to?
Plasma membrane receptors
What are the 4 types of plasma membrane receptors?
Ionotopic receptor (also acts as an ion channel)
Receptors that function as an enzyme
Receptors that directly alter enzyme activity, which is another protein
G protein coupled receptors
How many transmembrane spanning segments do G proteins have?
What happens when a substrate binds to a G protein?
- Part of it dissociates and interacts with other proteins (channel or enzyme)
- Causes the release of a second messenger within the cell
What kind of things can G proteins do?
Form active transport
What are some examples of proteins coupled to G proteins?
What does adrenylyl cyclase do?
Regulates cAMP (second messenger)
What does phopholipase C do?
Produces diacylglycerol and inositol triphosphate
Activates PKC and releases Ca2+ from internal stores
What do ion channels attatched to G proteins do?
Evoke slow IPSPs or slow EPSPs
What often acts as a second messenger?
Where are some sources of Ca2+?
Internal sources via IP3+ or Ca2+ stimulated releases from endoplasmic reticulum
Outside the cell by using voltage or ligand gated Ca2+ channels
Inhibition of Ca2+ transport out of the cell
What are some effects of Ca2+?
Directly effects proteins (like PKC)
Binds to calmodulin which activates protein target
Works via some other Ca2+ binding protein
What is pharmacology?
Study of drug action