8/24 Cell Signaling Flashcards
Define Endocrine
signaling to far away cells through hormones in the blood
Define paracrine
localized cell communication through secreted signals
Define Autocrine
cells signal themselves in a paracrine way
Define Neuronal signaling
similar to endocrine but fast and targeted to specific cells
Give an example of Endocrine signaling
Vassopressin and increasing water retention and blood volume
Give an example of paracrine signaling
hedgehog, Wnt and TFG-beta are examples
give and example of neuronal signaling
cell synapses
Diagrmam general G-Protein receptor pathway
a G-Protien receptor binds a ligand, then binds the G-protein, that then binds ATP (alpha subunit) and splits (from the Beta/Gama subunit) to activate something down stream. Then the GTP hydrolyzed, the G-protein sub-units come back together and it can start over.
Diagram general receptor tyrosine kinases pathway
When bind ligand the receptors dimerize. The intercellular domains interact as a tyrosine kinases and phosphorylate themselves. adaptor proteins bind and then two big pathways: Ras/MAP kinase (activate ras and lead to cell proliferation) and P13 kinase pathway (that changes PIP2 to PIP3 and activates TOR to lead to growth)
Diagram general nuclear hormone receptor pathway
cholesterol derived hormones and other hormones can enter the cell and bind nuclear receptors and directly alter gene transcription. or bind to guanylate cyclase!
what kind of reactions are catalyzed by kinases (potential effect)
Protein Kinases phosphorylate target proteins to :
- change the interaction with other proteins.
- Change conformation to active or inactive or different substrate
- Cause it to be digrated
what kind of reactions are catalyzed by phosphatases (potential effect)
de-phosphorylation through hydrolyze the bond with water. Reduce a signal or effect caused by a kinase.
what kind of reactions are catalyzed by guanylate cyclase (potential effect)
converts GTP into cyclic GMP or cGMP. this can activate protein kinases that phosphorylate targets to cause effect
what kind of reactions are catalyzed by adenylate cyclases (potential effect)
leads to the production of cyclic AMP (cAMP) from ATP. This in turn leads to protein kinase A being activated which can affect metabolism by shifting away from storing towards using glycogen
what type of reactions are catalyzed by phosphodiesterases (potential effect)
these tend to terminate a signal by degrading the second messenger level. Therefore: stop signal
what type of reactions are catalyzed by phospholipases (potential effect)
the hydrolisis of the PIP2 bond, freeing the IP3 from the membrane bound section
phospholipase C
activated by a G-protein complex. Hydrolyzes a phosphodiester bond of phosphorylated inositol away from PIP2 this creates IP3 mesanger and DAG that is stuck in the membrane still. IP3 changes allow opening of calcium channels. This turns on calmodulin that acts on many enzymes and transports.
how could signaling to a cell membrane receptor be advantageous to signaling to a hormone recewptor inside the cell
secondary messangers can diffuse to other parts of the cell.
The signal can be amplified.
crosstalk can result in input from many pathways connecting to a common second messenger therefore finetune signal.
rapidly degrade the signal by metabolizing second receptors
Protein Kinase C
down stream effector of diacylglycerol (DAG)
how do g-protein coupled receptor signal terminate
Galpha subunit hydrolyzes the bound GTP to GDP. Ligan disociated from receptor. internalize the receptor or break down the effectors etc.
