White Cell Communication 1 Flashcards
__ __ is cell to cell communication via extracellular signaling molecules binding to specific receptors in target cells to initiate a chain of events.
T/F: This signal transduction explains how complex cell behaviors can be regulated by signals from outside the cell?
Signal transduction.
True.
Two categories of responses occur via signal transduction. Describe them.
Fast response: change in activity/function of enzymes or proteins in cell.
Slow response: change in AMOUNT of proteins by change in expression in genes.
Name and describe 4 types of signaling:
Endocrine: long distance (freely diffusible) through bloodstream to target cells. long lasting.
Paracrine: acts locally, affecting nearby cells. short lived.
Synaptic: acts locally, affecting cells nearby. short lived.
Autocrine: signals onto the same cell itself. (growth factors in cancer cells)
Interpretation of the signals can result in what 4 different responses?
Survive, divide, differentiate, or die (apoptosis).
Signaling cascade components include these three categories of molecules:
- signals (ligands)
- receptors
- effectors
2 main categories of signaling molecules (ligands) are ___-philic and ___-philic molecules.
lipophilic (steroid hormones) and hydrophilic (growth factors).
gases (NO) can also be a signaling molecule.
Nitric Oxide (very unstable) binds to ___, influencing muscle relaxation, causing blood vessels to relax, increasing blood flow.
cGMP
The two general types of receptors fall under these two categories:
Most signaling molecules are of which variety?
Receptors bind to ligands with great specificity, aka __ __.
cell surface receptors and intracellular (steroids) receptors.
most are hydrophilic, requiring cell surface receptors.
high affinity.
Binding of hydrophobic ligands (cortisol, estradiol, testosterone, vit D3, thyroxine, retinoic acid) activates the receptor and initiates what process in the nucleus?
transcription of target genes.
GPCR stands for ___. They are composed of three domains ___, ___, and ___. What is the function of each domain?
A GPCR has how many membrane-spanning alpha helices?
G-Protein-Coupled Receptor.
Extracellular domain - binds to ligand.
Transmembrane domain - anchors receptor.
Cytoplasmic domain - associates with G-protein.
7.
One example of a GPCR effector is ___ ___, which generates cAMP, which goes on to interact with target proteins to cause the biological response.
The heterotrimeric G-protein has three subunits labeled:
adenylyl cyclase.
alpha, beta, gamma.
__ toxin targets a G protein.
How does cholera modify the G-protein, causing severe diarrhea?
cholera.
cholera keeps the G-alpha subunit in the GTP active form indefinitely = always active = constant pumping of Chloride ion and water out of the cell = diarrhea.
Different G-proteins in different locations can have different functions. One example is G-alpha(s) and G-alpha(i). What do they do?
G-alpha(s) - stimulates adenylyl cyclase.
G-alpha(i) - inhibits adenylyl cyclase.
In the fight or flight response, ___ induces activation of PKA . This generates a lot of ATP. What else occurs in different tissues like the liver, heart, and adipose tissue during the fight or flight response?
Is the epinephrine receptor a G-alpha(s) or a G-alpha(i)?
epinephrine.
liver: glycogen breakdown to glucose and inhibition of glycogen synthesis.
heart: increase contraction rate.
adipose tissue: hydrolysis of triglycerides to generate more glucose.
epinephrine stimulates the G-protein cascade, so it is a G-alpha(s).
___ refers to the process where a single ligand receptor can activate mutliple adenylyl cyclases, generating hundreds of cAMPs and PKAs, eventually phosphorylating 1000’s of proteins.
Amplification.
