Cell to Cell Communication Flashcards
Axonal growth in the nervous system is encouraged or inhibited by what kind of signaling?
Juxtacrine signaling.
Explain the growth of epithelial tumor cells, including the type of signaling involved.
EGF ligands bind to EGF receptors on the cell’s surface. This results in the increased production of VEGF (vascular endothelial growth factor). The VEGF molecules then diffuse out of the cell, and then interact with VEGF receptors on that same cell. This promotes growth of the tumor. AUTOCRINE SIGNALING.
What is intracrine signaling? Example seen in?
Generation of a signal intracellularly that will stimulate an intracellular receptor. An example is seen in estrogen-like molecules.
Explain GABA, including the type of receptor, what it causes to happen, etc.
An inhibitory neurotransmitter. Binds to GABA receptors, which are ligand-gated ion channels. Chloride moves into the cell, hyperpolarizing it.
The GCPR has how many membrane spanning regions?
7
What does the alpha subunit of the G protein do?
Binds to E1, and catalyzes the hydrolysis of GTP.
What does the beta-gamma subunit do in the G protein?
Binds to E2
What are the steps of the beta adrenergic cascade?
G(alpha-s) protein— think s for stimulatory
- epi/nore bind to GPCR
- GDP exchanged for GTP, activating the G(alpha-s) protein. This activates adenylate cyclase
- Adenylate cyclase makes cAMP from ATP
- cAMP activates PKA, which phosphorylates stuff.
Explain the activation of PKA
cAMP binds to regulatory subunits of PKA, and catalytic subunits are then released. The catalytic subunits are then free and active to phosphorylate stuff.
What does cAMP phosphodiesterase do?
It converts cAMP to AMP, meaning that cAMP can no longer activate PKA.
What are the steps of the alpha adrenergic cascade?
G(alpha-q) Protein
- Epi/nore bind to GPCR
- GDP exchanged for GTP, activating the G(alpha-q) protein. This activates phospholipase C
- PLC then catalyzes the formation of IP3, which binds to the ligand-gated calcium channel on the sarco reticulum, causing Ca++ release.
- PLC also synthesizes DAG from membrane bound lipids. DAG binds to protein kinase C (PKC), activating it to go phosphorylate targets.
What does Pertussis toxin do, and what does it target?
Inactivates the Gi-G Protein, which increases adenylate cyclase activation and thus increase cAMP levels.
What do Cholera toxin and E. Coli Enterotoxin target, and what happens?
Target G(alpha-s) GPCR, causing constitutive activation of adenylate cyclase. results in elevated levels of cAMP.
What does Tamoxifen do?
Binds to estrogen’s intracellular receptor, which prevents estrogen from binding. This stops estrogen from stimulating the proliferation of cancerous cells in the breast. Thus, used to treat BREAST CANCER.
Receptor guanylyl cyclases are an example of? What are the two types, and what are they associated with?
-Explain the activation of guanylyl cyclases.
Catalytic receptors, which have INTRINSIC ENZYME ACTIVITY. When a ligand binds to it, this enzymatic activity is seen.
Membrane bound form, as well as the cytoplasm-soluble form in the cytoplasm, which is regulated by nitric oxide.
- Ligand binds to its receptor, the guanylyl cyclase is activated which catalyzes the formation of cGMP from GTP. cGMP can then directly activate ion channels and indirectly activate cGMP-dependent protein kinases.
cGMP is involved in what? Has major effect on what?
Smooth muscle tone and neurotransmission (major effects on cardiovascular system).
what does cGMP phosphodiesterase do? What drug inhibits it?
Degrades cGMP to GDP. Viagra inhibits this enzyme allowing for more cGMP.
Elevated levels of cGMP does what do penile smooth muscle? Causes what to happen?
Relaxes it, allowing for erection.
What tumor-derived angiogenic factor causes the growth of endothelium on blood vessels?
Vascular endothelial growth factor.
Examples of ligands for nuclear receptors?
Vitamin D, steroids, retinoic acid, thyroid hormones.
which class of the nuclear-receptor superfamily primarily binds to DNA as a monomer?
Orphan receptors.
Nuclear receptor superfamilies:
steroid receptors are synthesized as what, and associated with what?
Synthesized in an inactive form, and associated with heat-shock proteins.
Nuclear receptor superfamilies:
Heterodimeric nuclear receptors bind DNA how? Examples?
Bind constitutively to DNA with RXRs as obligate partners. PPARs and LXRs are examples.
Oxytocin is is what type of signal?
endocrine and intracrine.
