Receptors - Overview
RECEPTORS OVERVIEW
Response speeds
- Fast
- Slow
Signaling pathways
- Intracellular
- Membrane-bound
Receptor classes
RESPONSE SPEEDS
Fast responses
- Due to altered protein function
- Occur in milliseconds to minutes
Slow responses
- Due to change in transcription and protein synthesis
- Occur in minutes to hours
Intracellular receptors
- Hydrophobic signaling molecules can travel through the plasma membrane (hormones)
- Receptors inside the cell
- Hormone/receptor complex travels to nucleus to bind DNA and promote a response
Membrane-bound receptors
- Receptor bound to membrane with binding site accessible to the extracellular space
- Ligand binds to receptors
- This causes receptor activation which activates further proteins within the cell
- Activated proteins transduce signal eventually leading to either altered gene expression or altered cellular metabolism
G-protein coupled receptors
- Receptor traverses the plasma membrane
- Ligand binds to receptor
- Receptor causes G-protein to bind GTP and become active
- Active G-protein induces further responses within the cell
Receptor tyrosine kinases
- Receptor traverses the plasma membrane
- Ligand binds to receptor
- Receptor dimerizes and phosphorylates itself
- Intracellular proteins are activated by binding the phosphorylated receptor
- Activated intracellular proteins induce further response within the cell
Ligand-gated ion channels
- Channel traverses the membrane in a closed conformation
- Ligand binds to channel
- Channel opens allowing ions to pass through
- Ions initiate intracellular response