inhibition and activation of receptors Flashcards
What are the steps of protein activation or inhibition in 4 general steps + examples for receptors
Molecules travels from sorces
- ligand
molecule interacts with protein
- binds to receptor (normally on plasma membrane)
causes activation or inhibition
- conformational change or blocked receptor
causes cellular effect
- signal transduction
What is the difference in pharmacology and toxicology
Pharmacology = the study of how drugs impact biological systems
Toxicology = study of how chemcials negativly effect biological systems
What are the normal two ways we class injested molecules
Positive effects = drug/medicines
negative effects = toxin/poision
What is the differences between enzymes and receptors
Enzymes:
- bind substrate
- change substrate to product
- 1 active site (normally)
- cytosol or membrane
Receptors
- bind ligands
- leave ligand unchanged
- many binding sites
- cytosol or membrane
What are the three types of receptors covered
+ structures of these receptors
receptor tyrosine kinases
- dimer = 2 chans
ligand gated ion channels
G-protein coupled receptors
- monomer weaved through PM 7 times, 3 loops top and bottom
- N external, C internal
Define an agonist and an antagonist
Agonist: A ligand which binds to receptor to cause a conformational change which then leads to a cellular effect via signal transduction
- often endogonous
Antagonist: A ligand which binds to a receptor to prevent the binding of an agonist to decrease signalling
- often exogenous
Define what a receptor and ligand are + types of ligands
Receptor is a protein or protein complex whicih regulates cellular processes via signaing
Ligands are chemicals whcih can be small molecules -> peptides which bind to a receptor to activate or inhibit activity
- Exogenous = external method of delivery - mostly antagonist
- Endogenous = made by the body - mostly agonists
What is signal transduction and 4 methods which can be used for it
Multistep process which give stime to coordinate and regulate processes
- proteins
- chemicals
- phosphorylation cascade
- 2nd messangers
What is a second messanger + some examples of these
A checmical which changes in concentraction to impact cullular regulation
cAMP, cGMP
diacytlglycrol
inositol triphosphate
What is a phosphorylation cascade
Many protein kinases phosphorylating further proteins down the line to cause cellular response
prosphatases used to dephosphorylate proteins to ensure repeatability + control of signal transduction
What are three methods of receptor regulation
- ligand dissociation , dependant on kenetics
- Internalization, endocytosed receptor so not used
- phosphatase
What is the signaling pathway for a GPCR
GPCR -> Gprotein made from alpha beta gamma subunit
alpha can be differen
- Gas = stimulatory to adenylate cyclase
- Gai = inhibitory to adenylate cyclase
Ligand bind -> conformational change -> G protein -> adenylate cyclase -> cAMP increase -> protein kinase A -> cellular response
What is the signalling pathway for a receptor tyrosine kinase
dimer whcih inteacts with adaptor protein
ligand bind -> conformational change -> phosphorylation -> phosphorylation of adaptor protein -> further interaction -> cellular effect
What is the signaling pathway for ligand gated ion channels
Ligand bind -> conformational change -> ions enter cell -> fast signal
- much faster than RTK or GPCR
What are two examples of GPCR signal transduction pathwasy
Glucagon: liver cells
glucagon binds to GPCR -> trigger GAS -> adenylate cyclase _> cAMP -> protein kinase A -> glycogen breakdown
GLP-1: pancreatic beta cells
binds to GPCR -> pathway -> insulin release
