GPCRs 2

Question 1

Membrane lipids may be targeted by receptor regulated lipases to generate 2 kinds of 2nd messengers :

Answer 1

(i) will be water soluble & diffuse through the cytoplasm eg. IP3
(ii) hydrophobic molecules, which remains in the membrane eg. DAG

Question 2

role of lipid kinases

Answer 2

Lipid kinases add phosphate groups to lipids eg. To DAG to make phosphatidic acid , or to PI to generate PIP, PIP2, PIP3

Question 3

what are PKCs

Answer 3

PKCs are Ser/Thr kinases , activated by DAG (C1 domain), and Ca2+ (C2 domain)

Question 4

what are PMAs?

Answer 4

PMA phorbol ester is an analogue of DAG used in research to activate PKCs

Question 5

how are PKCs activated

Answer 5

• DAG binding causes dissociation of intramolecular pseudosubstrate domain from active site
• Once activated PKCs can provide either Positive or Negative feedback in signaling pathway

Question 6

• 5 processes regulated by calcium signaling

Answer 6

• 5 processes regulated by calcium signaling
 Synaptic transmission
 Hormone secretion & synthesis in some cases
 Fertilization
 Muscle contraction
 Cytokenesis

Question 7

2 ways that calcium is regulated in the cell

Answer 7

A- Calcium influx into the cytosol is regulated by voltage gated and ligand gated channels in the PM and ligand gated channels in the ER.

B- Store operated channels made up of ORAI and gated by STIM are responsible for store refilling

Question 8

how is Information transfer encoded by calcium

Answer 8

Information transfer is encoded by the the amplitude, duration and frequency of store-released calcium signaling and translated by calcium-binding proteins to bring about changes in cell functions

Question 9

difference between L,N,P type calcium channels

Answer 9

all voltage controlled

L type - in skeletal and cardiac muscle, brain
N type - neurones and endocrine cells
P-type - purkinje neurones