Flashcards in Dr. White-Genes (when things go right and wrong) Deck (64)
What is signal transduction?
cell to cell communication
what happens if the lectin gene is knocked out? (mice used as example) What is this an example of?
if leptin is knocked out, the mouse will not think that it is full and will continue eating, resulting in a fat mouse. This is an example of signal transduction.
Describe endocrine signaling
long distance signaling, signal goes from bloodstream to distant target cells.
Freely diffusible signal and long lasting
Describe paracrine signaling
acts locally and affects nearby cells (not as freely diffusible)
short lived signal
Describe synaptic signaling
acts locally and affects cells nearby (not as freely diffusible)
short lived signal
Describe autocrine signaling
-cells respond to signals that they themselves release to cells of the same type
-cell secretes signal that feeds back and binds to a receptor on its own surface
ex: growth factor in cancer cells
Describe direct cell signaling
Ag-presenting cells to T cells
ex: immune cells
What does the extracellular domain of the G protein coupled receptor do?
binds to ligand
What does the transmembrane domain of the G protein coupled receptor do?
What does the cytoplasmic domain of the G protein coupled receptor do?
associates with G protein
G proteins are ______ proteins composed of how many subunits?
heterotrimeric, 3 subunits: alpha, beta, gamma
What do the heterotrimeric G proteins do?
regulate target enzymes
REVIEW THE PATHWAY OF G PROTEIN SIGNALING
slide 13 of lecture
What does adenylyl cyclase do?
generates cAMP which then goes on to interact with it''s target protein to cause a biological response
What occurs in cholera?
Cholera toxin modifies G protein by keeping the G alpha protein in the GTP active form indefinitely, making the pathway always active. Cl- and water pump out of cell in intestine, causing severe diarrhea.
cAMP interacts with target proteins to cause what?
a biological response
cAMP activate ______ which has ____ subunits
cAMP dependent protein kinase (PKA), 4 subunits
When 2 cAMP molecules bind to the regulatory subunits of PKA what happens?
release of active C subunits
Describe receptor tyrosine kinases (RTKs)
play important role in signal transduction
enzyme linked receptor
used for response to growth factors
What are the components of RTKs?
cytoplasmic domain which transmits signal through tyrosine kinase domain and adds phosphates to tyrosine on proteins
review signaling by protein phosphorylation
What happens when a ligand binds to the RTK?
causes conformational change which induces dimerization of two receptor monomers and autophosphorylation occurs
Autophosphorlyation of the the RTK causes what?
the receptor to act as a scaffold or docking sites to recruit other proteins to the plasma membrane, outside event (binding to receptor) gets transacted to a response inside the cell
review RTK cascade
review JAK-STAT process
review serine-threonine receptor and smad
when signal is not turned off, Ras is constitutively activated from a point mutation of Gly to ____ and results in what?
Val, resulting in mutation (frequently found in human cancer)
What makes cells different?
differences in gene expression
describe the helix turn helix DNA-binding domain structural motif
-two alpha helices connected by short chain of amino acids that make turn at fixed angle
-longer helix portion= recognition module-DNA binding module
- binds DNA as dimers