Session 5 - control of cytosolic Ca2+

Question 1

What are some examples of processes that Ca2+ regulates?

Answer 1

Fertilisation
Secretion
Neurotransmission
Apoptosis

Question 2

What is the EC [Ca]?

Answer 2

1-2mM

Question 3

What is the IC [Ca}?

Answer 3

100nM

Question 4

Name a high affinity, low capacity transporter on the cell membrane:

Answer 4

Ca2+ ATPase

Question 5

What is the negative feedback operation on Ca2+ATPase?

Answer 5

Ca2+ binds to calmodulin

Calmodulin binds Ca2+ATPase

Question 6

Name a low affinity, high capacity transporter on the cell membrane:

Answer 6

NCX
3Na to 1Ca
Reverses when membrane depolarised

Question 7

What is the SERCA pump?

Answer 7

Sarcoendoplasmic Ca ATPase

NOT REGULATED BY CALMODULIN

Question 8

Why does Ca diffuse more slowly than would be expected?

Answer 8

Due to IC Ca buffers

Speed of diffusion depends on conc. of binding molecules and their level of saturation

Question 9

What allows a rapid influx of Ca across the plasma membrane?

Answer 9

VOCCs

Ligand gated Ca channels

Question 10

What is calcium induced calcium release?

Answer 10

Calcium enters the cell
Interacts with ryanodine receptors
Ca released from SER