Lecture 3: cell signaling Flashcards
receptor specificty
- cells only respond if they have the correct receptor
- chemical messengers can activate multiple receptor types, with each having a different response
ligand
a molecule that binds to a receptor
endogenous ligand
hormone or NT produced by the body
agonist
a molecule that binds to a receptor and activates it
antagonist
a molecule that binds to a receptor and blocks it, preventing activation by an agonist
water-solube messengers generally have a receptor on the ___, while lipid-soluble messengers generally have a receptor in the ___
cell surface; cytosol/nucleus
function of a nuclear receptor
- inactive receptor in cytosol or nucleus
- activated receptor translocates to nucleus and binds DNA
ligand-gated ion channels
- agonist binds causes channel to open
- main effect is change in membrane potential
- in: depolarize
- in: hyperpolarize
enzyme-linked receptor mechanism
receptor has enzyme activity that phosphorylates target proteins in cell
JAK/STAT pathway mechanism
- Receptor activates JAK which goes on the phosphorylate proteins in the cytoplasm
- often transcription factors that go to nucleus
G protein-coupled receptors (GPCRs)
- Has 3 subunits
- Activated alpha subunit binds GTP and dissociates from beta and gamma
- goes on to activiate enzymes and ion channels
Gs action
stimulates adenylyl cyclase, increases cAMP
adenylyl cyclase
enzyme that makes cAMP from ATP
cAMP
2nd messenger that activates cAMP-dependent protein kinase (PKA)
Gi action
inhibits adenylyl cyclase, decreases cAMP
