Topic 8 Flashcards
Signaling cell
Releases message
Ligand
Sents the message to the receptors on the target cell
Target Cell
Receives the message from the Signaling Cell
Autocrine
Auto: self
A cell that communicates with itself
-Uses exocytosis and diffusion through extracellular spaces
Target cell and signaling cell are the same cell
Direct (via gap junctions or plasmodesmata)
physical connection between the cells
-Target cell and signaling cells are touching through physical contact
Paracrine
Para: near or next to
-Target cell is nearby (<20 cells away)
-Uses exocytosis and diffusion through extracellular spaces
Endocrine
Endo: inside
-long distance communication
-Target cell is farther (>20 cells away)
-Uses exocytosis and diffusion through extracellular spaces
Inactive state
receptor is not triggering response from the cell
-When the voltage-gated channel is blocked and the ions are not even entering the channel (inactive and ready to respond)
-The voltage-gated channel can be open but is blocked at the other end, the ions cannot get through the full channel (Inactive and not ready to respond)
Active state
receptor is triggering response from the cell
-the voltage-gated channel is fully open and ions can flow through freely (active, triggering response in target cell)
Amino acids bind where?
Bind to the cell surface receptor
Cholesterol binds where?
Binds to the internal receptor
Peptides bind where?
binds to the cell surface receptor
Receptor Tyrosine Kinases
-Tyrosine tells me amino acids are present
-Kinases tells me there is enzyme activity present
-This receptor has tyrosine (amino acids along the chain) that are phosphorylated (phosphate groups added) using ATP (cellular energy)
-Intergral membrane protein that has kinase
Tyrosine Kinase Response
Activation of second messenger system which may lead to changes in ion membrane permeability increased or decreased…
Transmembrane proteins
Type of membrnae protein that spans across the entire membrane
-Trans: across
Receptor
Intergral membrane protein that is also an ion channel
Ion channel coupled
this receptor has an ion channel (transport protein) that allows ions/charged atoms through
-Example: Nicotinic Acetycholine Receptors (Ligand Based Receptors)
Signal
Highly variable by receptor (voltage, mechanical, ligand, and photo stimuli)
-Example: Acetylcholine
-Usually a Ligand (chemical)
Response
Fast, controlled. select ion movement across the membrane, changes proportion of charges
G protein (coupled with receptor)
Peripheral protein associated with intracellular surface of plasma membrane
-G protein-coupled/linked receptors, there is a receptor that works closely (right next to each other) with a G protein to do its job
Steps of GCPR
- Ligand Binds to GCPR
2.GCPR undergoes confirmational change
3.The alpha subunit exchanges GPP for GTP
4.Alpha subunit dissociates and regulates target proteins
5.Target proteins relay signal via secondary messenger system - The G protein subunit breaks down GTP into GDP and becomes deactivated
- Removal or breakdown of ligand from receptor/ or deactivation of secondary messanger system causes subunit to regroup into the inactive timer state
Target Cell Receptor Steps
- Receptor activation leads to activation of second messengers
- Receptor autophosphorylates
- Receptor is inactive
- Receptor dimerizes
