Cell Bio 406 Lecture 8
What is cell signaling?
how a cell gives and receives messages to environment and with itself.
Why is cell signaling necessary?
cell survival depends on processing information.
What is the more studied form of cell signaling?
canonical WNT signaling
What is a WNT ligand?
protein that signals cell
What is endocrine signaling?
originate from far away from receiving cell
What is paracrine signaling?
signals from nearby cell
What is autocrine signaling?
originate from same cell.
What is reception?
signal detection occurs when ligand binds to receptor inside or outside cell
What is transduction?
relay of received signal
What is response?
final outcome of the received signal
How are membrane receptors activated?
dimerization and phosphorylation
What are intracellular receptors?
receptors inside cell that bind to small molecules that pass the plasma membrane
Why is transduction multistep?
permits signal amplification and enhanced regulation
What is a second messenger?
relays signal received by receptor
What does kinase do?
what does phosphotase do?
What are the various responses to signaling pathways?
molecularly- changes gene expression and protein function
cellularly- cell proliferation, senescence, death and migration
What are the parts of a receptor?
lingand-binding domain and effector domain
What does a silent antagonist do?
makes ligand void
What does a full agonist do?
maximal biological resoponse
what is a partial agonist?
What is inverse agonist?
What are essintial for signal transmission?
What are adaptors?
consist of binding domains or motifs only.
What is Grb2?
growth factor receptor bound protein 2- adaptor with SH2 and SH3 to transduce EGFR signal
What are adaptor proteins?
link signaling molecules and target them in a manner that is responsive to extracellular signals.
What is homologous desensitization?
one feedback loop
what is heterrologous desensitization?
feedback loop effects two receptors
How are activating and deactivating reactions controlled?
by different regulatory proteins
Why are activation and deactivation separate?
allows for fine tuning of amplitude and timing.
What are second messengers good for?
quick diffusion within cell.
What is a second messenger-stimulates protein kinase?
tetramer of two C and two R subunits
What do regulatory subunits do in PKA?
What does R bind?
What happens when cAMP is highly concentrated?
R dissociates rapidly
What does Ca2+ do?
serves as second messenger and regulatory molecule for calmodulin
What controls concentraion of Ca2+?
organellar sequestration and release
What does Pl3-kinse do?
regulates cell shape and activation of growth by phosophorylating lipids that change activity
Where do nuclear receptors bind?
to hormone response elements in the 5' UTR
How is retinoic acid signals mediates?
by nuclear receptors
WHat are G=protein signaling modules?
consist of a G-protein, receptor, and and effector protein to initiate diverse cell functions
What controls heterotrimeric G proteins
regulatory GTPase cycle
When are heterotrimeric g proteins activated?
When Ga subunit binds GTP
What inactivates G protein?
GTP hydrolysis to GDP
What accelerates GTP hydrolysis?
GAPs- GTPase-activating proteins.
What are GAPs for g proteins?
RGS and phospholipase C-bs
When are GTP=binding proteins active?
When bound to GTP
What promotes activation?
GEFs- guanine nucleotide exchange factors
What promotes deactivatoin?
What slows spontaneous nucleotide exhange?
GDP dissociation inhibitors- GDIs
Waht does Rho do?
functions as a molecular switch
What is key regulator of cell adhesion?
What increases accumulation of actin filaments to lateral walls of cells?
Cell Bio 406 Lecture 8