Biological signalling and receptors - drug targets Flashcards
What are the types of signalling between cells via chemical messengers?
- Paracrine
- Endocrine
- Synaptic
What are the subdivions of sinalling molecules?
- Local chemical mediators
- Hormones
- Neurotransmitters
* classification still useful but no longer holds
What is a receptor?
A molecule that recognises specifically a second molecule or family of molecules which in response to ligand binding brings about regulation of cellular process
What is a ligand?
Any molecule that binds specifically to a receptor site
What is the role of receptors in cellular physiology
- Cellular delivery
- Neurotransmission
- control of gene expression
- Cell adhesion
How are receptors classified?
- Specific agonist recognised
- Affinity of a series of antagonist
What is the difference between receptor and acceptor?
Receptor
- Silent at rest
- agonist binding stimulates biological response
Acceptor
- Operate in absence of ligand
- Ligand binding alone produces no response
Give examples of ligand gated ion channel?
- Nicotinic acetylcholine receptor (nAChR)
- GABA
- IP3 *non classical
Give examples of Receptor Tyrosine Kinase
- Grwoth factor receptors
- Insulin receptors
What are the two domains for Receptor Tyrosine Kinase?
- Binding domain
- Catalytic domain
Describe the mechanism of Receptor Tyrosine Kinase
- Ligand binds to RTK
- Causes neighbouring RTK to associate with each other and form cross-linked dimer
- Each RTK in dimer phosphorylates Tyrosine on other RTK
- Enzymatic domain serve as docking platform for different intracellular proteins involved in signal transduction
- Different proteins attach to physphorylated tyrosine
- * proteins must have SH2 Domain to dock with phosphorus
Give examples of GPCRs
- a1 adrenoreceptors
- M1 muscarinic acetylcholine receptos
What are the two domains in GPCR?
- Binding domains
- G-protein coupling domain
What type of ligands are intracellular receptors for?
Hydrophobic molecules
Eg ; Oestrogen, progesteron, cortisol
Give examples of intracellular receptors
- Oestrogen receptors
- Progesteron receptors
What are the two domains for intracellular receptors?
- Binding domain
- DNA binding domain
Describe the mechanism of intracellular receptors
- Hormone travel through cell membrane and binds to hormone receptor in cell
- Inhibitory protein complex released and DNA binding site exposed
- Hormone bound receptor travel into nucleus and attach to specific region on DNA
- mRNA produced and transported into cytoplasm
- mRNA translated into protein
