Ch 17 Signal Transduction and Pharmacokinetics Flashcards
signal transduction
chemical signals are releases from one cell then binds to a receptor on another cell
signals only bind to their specific receptor
second messenger systems
adenylate cyclase - cAMP
phospholipase C - PIP2 DAG IP3 (Ca++)
direct gene interactions
steroids
cAMP pathway
1) chemical signals bind to G protein coupled receptor, next to G protein (in plasma membrane)
2) GTP binds to the G protein and the whole structure moves so the G protein can activate adenylyl cyclase
3) there, it takes ATP and strips two phosphates to become cAMP
4) cAMP affects chance within cell by activating protein kinases inside cell which changes cell function
PIP2 DAG IP3 pathway
1) chemical signal binds to G protein coupled receptor
2) G protein activates protein kinase C
3) PIP2 gets broken into DAG and IP3
4) DAG activates PKC to alter cell function
5) IP3 goes to ER to bind to Ca++ channels and open them
6) Ca++ affects changes in cell
steroid pathway (small nonpolar molecules)
1) steroid enters cell unassisted
2) binds directly to genome to affect protein synthesis
avidity
how long a ligand stays once its there
affinity
how well a ligand fits in a receptor
how long a signal stays in blood
half life (affected by amount of enzymes in liver)
steroids in blood
some need transporter due to blood 50% water (small nonpolar)
the more often a ligand is in a receptor…
…the longer the signal is transmitted
synergism
multiple signals being transmitted for a bigger effect
blockers
high affinity but prevents true ligand from binding and prevents signals (one example of antagonism)
example of antagonism
two opposite signals binding and cancelling each other out
permissive
two ligands binding at the same time to cause an effect (one signal on its own will not do it)
