CellSig8 - 10

Question 1

What is the Ca wave in the egg caused by?

Answer 1

Phospholipase C in the sperm

Question 2

What is special about Ca as a signalling molecule?

Answer 2

Never created or destroyed - only its concentration is controlled

Question 3

How is cytosolic Ca kept low?

Answer 3

Na-driven Ca exchanger (nerves/muscles), PMCA (PM Ca ATPase), SERCA (SER Ca ATPase), Ca uniporter (mitochondrion)

Question 4

Characterise SERCA1-3

Answer 4

1+2 in types of muscle, 3 in non-muscle cells

Question 5

What is thapsigargin?

Answer 5

Selectively inihibits SERCA activity

Question 6

How is cytosolic Ca increased?

Answer 6

Voltage dependent Ca channels in PM, IP3-gated allow escape from ER, ryanodine receptors release Ca from sarcoplasmic reticulum

Question 7

What inhibits the IP3 Ca release pathway?

Answer 7

Ethanol and caffeine - relaxants

Question 8

Why is calmodulin very important?

Answer 8

1% of cell protein, activates MLCK, allows myosin head to interact and thus facilitates contraction of muscle

Question 9

Outline MLCK cycle

Answer 9

Inactive + Ca-calmodulin > activated + auto-phosphrylation > fully active > Ca independent > dephosphorylation > inactive

Question 10

How is MLCK involved in memory?

Answer 10

Activation = memory of prior Ca pulse. Used in vertebrate nervous system