Signal transduction pathways Flashcards
what are signal transduction pathways
link between cell/tissue and the external environment
what is step 1 in STP
release of primary messenger
what is step 2 in stp
reception
what is step 3 in stp
relay of information
what is step 4 in stp
activation of message- physiological response
what is step 5 in stp
signal termination
where is the receptor located
in the membrane
how many domains does the receptor have
extracellular and intracellular domain
the extracellular domain is specific to
the receptor
when the receptor binds to hormone/signal what happens
triggers structural changes to convey the message to the inside
where does the primary signal go
to the specific receptor on the membrane
first messengers are usually
hormones
what are examples of hormones
peptides ( insulin) gas (NO) neurotransmitter (acetylcholine) cholesterol derivative
what changes in the receptor leads to production of small molecules that serves as secondary messengers
structural changes
how do we get secondary messengers
structural changes in the receptor
which is more produced
primary or secondary messengers
secondary
what are some examples of secondary messengers
cAMP cGMP Ca++ IP3 Diacylglycerol
responses to primary messengers would include
alteration of cellular and molecular activites by
covalent modification
conformational changes
alteration of protein expression
who is affected with there is a response to the primary messengers
pumps
enzymes
gene transcription factors
processes such as nerve transmission
what must happen after the response
the original signal must be terminated
one primary messenger can produce
a 50 million fold
what are the three classes of receptor proteins
7TM dimeric receptors (recruit protein kinase) dimeric receptors (they are protein kinase)
what is the first step of 7TM
cytoplasmic domain conformation change when bond with messenger, activating G protein
7tm: what happens when g protein becomes activated
GTP binds instead of GDP
7TM: what happens when Gprotein becomes GTP
dissociates and binds to adenylate cyclase activating it
7TM: what happens when adenylate cyclase becomes activated
activates ATP and turns into cyclic amp and then cyclic amp phosphorylates protein kinase A
7TM: what happens when cAMP is activated
phosphorylates protein kinase A
7TM: how does GTP become GDP
has internal clock and hydrolyzes to GDP
causes Galpha to dislocate and attach to beta and gamma
when Galpha dissociates from adenylate cyclase does the cascade stop
no because there are still cAMP phosphorylating protein kinase A
7Tm: who is the secondary messenger
cAMP
7TM: how do you inactivate the secondary messenger
cAMP phosphodiesterase
7TM: how does protein kinase A become inactive
special enzymes remove phosphate group
7TM: when hormone eventually dissociates from receptor, what protein comes along and phosphorylates it to lock in the inactive state
GRK2
7TM: where does GRK2 connect to
carboxy terminal of ser and thr
7tM: what second protein comes to GRK2 to help phosphorylate it
beta arrestin
how does cholera toxin work
“A” subunit binds to G protein and locks in GTP causing PKA to become phosphorylated and always active
how does pertussis toxin work
locks Galpha in GDP
dime:tyrosine has what type of units
alpha: binds to insulin
beta: subunit in cytoplasm which is a tyrosine subunit kinase
what makes the receptor molecules interesting in dime:tyrosine
they have to come together to bind to insulin
does the insulin bind to one alpha subunit or two
one
what happens with the two alpha subunits are close together
beta subunits are close together and cross phosphorylate activating them
what binds to the beta unit
irs
does the irs have tyrosine residues
yes
who binds to irs when phosphorylated
PI3k
PI3k activates who and what
PIP3 who is the secondary messenger
PIP3 activates??
PDK1
what type of kinase is PDK1
tyrosine
when PDK1 becomes phosphorylated and activated what happens
activate Akt/PKB
what type of kinase is PKB
ser/thr
who does AKT/PKB activate
glut 2 and glut 4
how are signals terminated in dimeric
phosphatases
tyrosine phosphatases affect
irs and pi3k
lipid phosphotases affect
pip3
serine phosphotase affect
AKT/PKB
in HGH what protein kinase is associated with cytoplasmic domain
JAK2
JAK2 binds to what and does what
STAT5 which deals with regulating gene expression
inositol/ca+ binds to what
7tm
in inositol the receptor activates a
gprotein
inositol: the gprotein activates what
phospholipase c
who does phospholipase c activate
DAG and PIP3 (both secondary messengers)
who does pip3 bind to in inositol
calcium channel on er
who does DAG activate
PKC
how does nuclear receptor signaling work
lipophilic mesenger binds to receptor
conformational change
dna binding and transcription of specific genes is activated
what a glucocorticoid
used in nuclear receptor signaling
cholesterol derived
used in many drugs
