What are the 3 types of local signaling?
1) Intracellular
2) Cell surface
3) Paracrine and synaptic
What is intracellular signaling?
- Signaling through two cells that are touching each other
- Signaling molecules are small and cross through gap junctions/plasmodesmata
How do intercellular receptors work?
- Located inside the cell (intracellular matrix)
- Float in the cytoplasm
- Hormone must be small and hydrophobic to go through the membrane
What is cell surface signaling?
- Signaling through the ligand of one cell attached to the receptor of another cell (but the cells are not physically touching)
What is paracrine and synaptic signaling?
- Signaling through nearby cells (not touching whatsoever)
- Signaling molecules are secreted into the cytoplasm and diffuse nearby cells
- Synaptic signaling occurs in the synapse
What is the one type of long distance signaling?
Endocrine signaling
What is endocrine signaling?
- When endocrine cells secrete hormones that travel long distances in the blood stream
- It will go to different receptors on different target cells
What is reception?
- Signaling molecule (ligand) binds to receptor
- Receptor changes in response to binding (shape & location)
What is transduction?
Relaying a message. Letting the body know I’ve received the signal.
What is response?
When the cell does something based on the signal
Explain how the G Protein-Coupled Receptor (GPCR) functions.
1) Signal molecule binds to site
2) G protein, carrying GDP, connects to G Protein Coupled Receptor: activated. (GDP is given off).
3) G protein, carrying GTP, connects to the inactive enzyme (activating it).
4) Cellular response (GTP is given off and the cycle restarts)
What will happen to GPCR signaling if [GTP] is low?
The signal will not be transduced to the enzyme
What are receptor tyrosine kinases (RTK)?
Proteins
Explain how RTK functions.
1) Two RTK proteins accept signaling molecules.
2) The two proteins are activated and they join to form a dimer.
3) ATP, from inside the cell, attaches phosphates to the tyrosines.
4) Cellular response
Is RTK endergonic or exergonic?
Endergonic
It requires ATP
What are ion channel receptors?
Proteins with gated channels
Explain how the ion channel receptors function.
1) Gate closed.
2) Signal molecule binds to active site.
3) Gate opens.
4) Ions flow down their concentration gradients from the extracellular matrix into the intercellular matrix.
5) Cellular response
An increase in cholesterol that decreases membrane fluidity will slow signaling for which receptors proteins?
- G Protein-Coupled Receptors
- Receptor Tyrosine Kinases (RTK)
- Ion Channel Receptors
What’s an example of reception?
G Protein-Coupled Receptors
- vision, smell, taste
- if something binds with it, it’s folding changes
What are the 3 stages of cell signaling?
1) Reception
2) Transduction
3) Response
