ICPP4 - Effector Mechanisms Flashcards
Give some examples of effectors which are enzymes.
Adenylyl cyclase, phospholipase C, PI3K, cGMP phosphodiesterase
Give some examples of effectors which are ion channels.
Voltage operated Ca2+ channels and G protein regulated inwardly-rectifying K+ channels.
What is produced when ATP is converted to cyclic AMP by adenylyl cyclase?
Cyclic ATP dependent protein kinase.
Cyclic AMP exerts most of its actions through cyclic AMP dependent protein kinase. What does this enzyme do to target proteins in the cell?
It phosphorylates them.
Which enzyme is used for this reaction?
ATP -> cyclic AMP
Adenylyl cyclase
Which enzyme is used for this reaction?
PIP2 -> IP3 + DAG
Phospholipase C
Ca2+ conc. is high outside the cell and low inside, but which organelle has a high Ca2+ conc.?
Endoplasmic (or sarcoplasmic) reticulum
What are increases in cytoplasmic Ca2+ concentration mediated by?
Movement of Ca2+ across the plasma membrane and release of Ca2+ from the ER/SR.
Which three things oppose an increase in cytoplasmic Ca2+ conc.?
Relative impermeability of plasma membrane to Ca2+, pumps and transporters move Ca2+ out of cytoplasm, Ca2+ buffer proteins.
Name the two ATP dependent pump mechanisms in the plasma membrane.
PMCA (plasma membrane Ca2+ ATPase) and SERCA (SR/ER Ca2+ ATPase).
What is the short name given to the transporter that exchanges Na+ and Ca2+ in the plasma membrane?
NCX
Which two mechanisms allow Ca2+ to move in through the plasma membrane?
Voltage operated Ca2+ channels and ligand-gated ion channels.
Which two mechanisms allow Ca2+ movement out of the ER/SR?
CICR/ryanodine receptors and IP3R receptors.
Phospholipase C catalyses the cleavage of PIP2 into two second messengers - what are they called?
IP3 and DAG.
Explain how signal amplification leads to a relatively massive cellular response to a few molecules of adrenaline?
Activation of adenylyl cyclase generates many molecules of cyclic AMP which then activate PKA.
