lipid signalling

Question 1

what determines the cellular response

Answer 1

the net concentration of the second messenger

Question 2

what are first messengers

Answer 2

growth factors, hormones, ECM, receptors

Question 3

what are second messengers

Answer 3

small molecules

Question 4

what are some widely used second messengers

Answer 4

cAMP, Ca2+ ions and phosphoinositides.

Question 5

how do phosphoinositides mediate different membrane events

Answer 5

act as signalling complexes in signalling pathways and act as ion channels, transporters, ion pumps in membrane protein acitvity. can also modulate vesicle fission and fusion. lipid transfer protein activity.

Question 6

where are the 3 places phsphoinositides can be found

Answer 6

endosomes, golgi, plasmamembrane

Question 7

what is the structure of PIP2

Answer 7

glycerol backbone, 2x fatty acyl chains attached. inositol sugar attached via phophate

Question 8

what PIP2 hydrolysed by and why is it important

Answer 8

phospholipase C hydrolyses it to DAG and IP3

Question 9

what does membrane bound PI do

Answer 9

recruits effectro protein to membrane where they interact with G-protiens

Question 10

what is IP3

Answer 10

water soluble molecule. binds and opens Ca2+ channels in ER raises Ca2+ concentration in cytoplasm

Question 11

what is DAG diacylglycerol

Answer 11

in membrane has 2 siganlling roles. when cleaved releases arachidonic acid and can activate protein kinase C by inducing translocation to plasma membrane

Question 12

name a powerful second messenger and regulator og calcium flux

Answer 12

InsP3

Question 13

what are some general observations of phospholipase C

Answer 13

PH domain binds PI lipids, C2 domain binds membranes when there is calcium ions, RasGEF promotes GTP exchange and activation of Ras proto-oncogene, EF binds calcium ions

Question 14

name the different functions of the different C domains

Answer 14

C1-binds DAG lipid, C2-binds membranes in presence of calcium ions, C3 BINDS atp, C4 binds substrate for phosphorylation by kinase domain,

Question 15

what is the function of class 1 PI3K

Answer 15

localised to plasma membrane and endosomes

Question 16

function of class II PI3K

Answer 16

in golgi and secretory pathway

Question 17

function of class III PI3K

Answer 17

in endosomes and golgi membrnaes

Question 18

function of PI4K

Answer 18

in golgi and endosomes

Question 19

what is phosphoinositdes bind pleckstrin homology domains (PH)

Answer 19

kinase C substrate in platelets.

Question 20

what are eicosanoids

Answer 20

act near site of synthesis and catabolised rapidly. has specific physiological effects on target cells

Question 21

what are prostaglandins

Answer 21

respond in injury or damage. control inflammation, blood flow, formation of clots and labour induction.

Question 22

what are leukotrienes

Answer 22

respond in immune response. accompanied by production of histamine and prostaglandin. potent action on smooth muscle.

Question 23

what are the effects of sphingomyelin

Answer 23

apoptosis, proliferation, inflammation, angionesis

Question 24

what does ceramide regulate

Answer 24

cell stress

Question 25

what does ceramide 1 phosphate activate

Answer 25

phospholipase A2 which stimulates production of arachidonic acid.

Question 26

what is glucosylceramide implicated in

Answer 26

post golgi trafficking and drug resisitance in cnacer.

Question 27

what does sphingosine interact with

Answer 27

protein kinase H regulates actin dynamics, cytoskeleton, endocytosis, cell cycle and apotosis.

Question 28

what does sphingosine 1 phoospahte have effect on

Answer 28

endothelial cell growth, movement and inflammation.