Lecture 20 Flashcards
Cell to cell signaling regulates what?
gene expression
metabolism
cell shape and cellular migration
neuronal signaling
What are the properties of cell surface receptors?
hormone hydrophilic extracellular domain for binding intracellular domain is for signal transduction have secondary messengers rapid response
examples of ligands that use cell surface receptors?
insulin
glucagon
epinephrine
acetylcholine
What are properties of intracellular receptors?
lipophilic (diffuse through membrane) located in the cytoplasm or nucleus conformational change on binding H-R complex enters nucleus bind to specific regions of the DNA influence gene expression response is much slower
Examples of ligands that use intracellular receptors?
steroid hormones
thyroxine
vitamin A and D
What are the three types of intercellular signals?
- endocrine
- autocrine
- paracrine
Explain endocrine signaling and examples of ligands?
hormone is secreted into the blood
Ex: insulin
Explain autocrine signaling and an example?
self activation or repression
Ex: growth factors
Explain paracrine signaling and an example?
secretion of molecules to nearby cells
Ex: neurotransmitters
What are the features of intracellular signal-transduction?
- Specificity
- Amplification
- desensitization and adaptation
- integration
What are the four basic types of signal transduction pathways?
- intracellular receptor (steroid receptor)
- gated ion
- receptor enzyme (catalytic receptor)
- receptors that form intracellular secondary messengers
Examples of ligands that use intracellular receptors?
- testosterone, estrogen, cortisol, aldosterone
- vit A and D
- thyroid hormone
What is the steroid receptor mechanism?
- hormone diffuses into the cell
- binds to its specific receptor
- H-R complex enters nucleus and binds to specific region
- can lead to induction or repression of a gene
slow response
How does a ligand gated channel work?
binding of the ligand leads to the opening of the channel
results in an influx of ions
alters membrane potential
examples of ligand gated channels?
- nicotinic ACh
- glutamate receptors
- GABA-A receptors
- glycine receptors
How does the tryosine kinase receptor work? What kind of receptor is it?
It is a catalytic receptor
- ligand binds
- receptor is activated
- The receptor is phosphorylated with kinase
How does the insulin receptor work?
- insulin binds to the receptor
- insulin actives the receptor
- The receptor is phosphorylated or activated
tyrosine kinase is what activates the receptor
What are the cellular responses to insulin binding to the tyrosine kinase receptor?
increased glucose intake
regulation of transcription
activation of enzymes and regulation of metabolism
Explain the process of GLUT-4 and insulin interaction?
- insulin binds to the receptor
- GLUT 4 translocated from the golgi to the PM
- Vesicle containing GLUT4 binds and fuses with PM
- glucose transport allowed in response
- insulin dissociates; inactivation
- vesicle containing GLUT4 translocates back to golgi
What types of receptors form second messengers?
G-protein couple receptors
guanylate cyclase (cGMP)
What are examples of G-protein receptors?
- Alpha1 adrenergic receptor
activates phospholipase C
increases IP3, DAG, and Ca
- Alpha2 adrenergic receptor (inhibitory)
inhibits adenylate cyclase and decreases cAMP levels
- beta-adrenergic receptor (stimulatory)
activates adenylate cyclase and increases cAMP levels
