Cell Signalling

Question 1

what are RTKs mainly involved in?

Answer 1

cell survival, differentiation, proliferation.

Question 2

what are phosphoinositides and why are they important?

Answer 2

lipid containing phosphorylated inositol derivatives 
important for signal transduction 
pip2 --> dag + ip3 
pip2 --> pip3 via pip3 kinase 
pip3 --> pip2 via pten

Question 3

Outline the PI3 kinase Akt pathway.

Answer 3

RTKs activate pi3k
pip3 recruits akt & pdk1 to membrane
pdk1 & mTor phosphorylate & activate akt
akt phosphorylates Bad
Bad THEN inhibits apoptosis.

Question 4

What is the role of SERCA?

What is the role of PMCA?

Answer 4

an ATPase which transfers calcium from cytosol to SR during muscle relaxation.

At physiological []s transports one Ca out of cell using one ATP.

Question 5

What is the concentration gradient of Ca?

Answer 5

Extracellular ~1.5-2 mM
Intracellular ~100nM
ER ~0.5mM

Question 6

what is significant about CICR in ER channels?

Answer 6

IP3 receptors activated by IP3 in the presence of Ca but inhibited at []s greater than 300nM.

Question 7

what happens in gene transcription as a result of Antigen binding a T cell receptor?

Answer 7

Ca/CaM activates calcineurin
Calcineurin dephosphorylates NFAT
NFAT translocates to nucleus & initiates transcription.