Signalling Flashcards
What are the 4 classes of secondary messengers? Give an example of each
1) cyclic nucleotides - cAMP, cGMP
2) lipid bilayer derived molecules - inositol-1,4,5-triphosphate (IP3), diacylglycerol (DAG)
3) gases - nitrous oxide, carbon monoxide
4) ions - calcium
what is the precursor and effector enzyme for cAMP
precursor - AMP; enzyme - adenylate cyclase
what is the precusor and enzyme for IP3 and DAG
precusor - phosphatidylinositol-4,5-biphosphate; enzyme - phospholipase C
describe the sequence of events following BDNF binding
1) tyrosine kinase receptors dimerise, kinase domains phosphorylate each other and then tyrosine residues
2) tyrosine residues bind GRB2 which binds SOS which binds Ras causing it to exchange GDP for GTP
3) GTP bound Ras dissociates, binds and activated Raf
4) Raf activates MEK which activates ERK which causes change in gene expression
how many isoforms does adenylate cyclase have
8
where is adenylate cyclase found
bound to plasma membrane
which type of g protein activates adenylate cyclase
G alpha s
which g protein inactivates adenylate cyclase
g alpha i
which ion can activate some isoforms of adenylate cyclase and inactivate some
Calcium
sustained increased in calcium can cause apoptosis. true or false?
True
which enzymes are activated by calcium which cause apoptosis
proteases, phospholipases, endonucleases
calcium induced apoptosis is associated with an increase in signalling by which neurotransmitter
glutamate
what are some of the ways calcium is removed from the cytoplasm
1) plasma membrane ATPases hydrolyse ATP to pump calcium out
2) smooth endoplasmic reticulum ATPase hydrolyses ATP to pump calcium into smooth endoplasmic reticulum
3) ion exchangers use energy from Na/K electrochemical gradients to pump ca out
what are some of the ways calcium is let into the cell
1) calcium permeant channels - voltage gated calcium channels, ligand gated calcium channels
2) IP3 binds to receptors on smooth endoplasmic reticulum to release calcium into cytoplasm
