Intro to Ca2+ homeostasis

Question 1

What is the normal blood serum calcium levels?

Answer 1

8-10 mg/dL or 1.9-2.3mM

Question 2

GIve examples of Ca2+ homeostasis regulation in the body

Answer 2

• Intestinal Ca2+ uptake
• Ca2+ reabsorption in kidney
• Bone calcium regulation

Question 3

Give examples of Ca2+ homeostasis regulation under endocrine control

Answer 3

• Ca2+ sensing receptors in parathyroid gland
• Parathyroid hormone

Question 4

State the importance of [Ca2+] regulation

Answer 4

• Muscle contraction
• Neurotransmission
• Hormone regulation
• Fertilization
• Learning and memory

Question 5

List examples of proteins involved in decreasing [Ca2+] in cell

Answer 5

ATP dependant

• PMCA (plasma membrane Ca2+ATPase)
• SERCA (sr/er Ca2+ ATPase)

Non ATP dependant

• NCX (Na-Ca exchanger)

Question 6

List examples of proteins that are involved in increasing [Ca2+] in cytoplasm

Answer 6

​Plasma membrane

• LGIC
• VOCC

ER/SR

• IP3R
• CICR

Question 7

What are the basal level concentrations of free Ca2+ ions in EF, ER lumen and cytoplasm?

Answer 7

• EF : 1 x 10^-3 M
• ER : 2 x 10^-4 M
• Cytoplasm : 1 x 10^-7 M

Question 8

How Ca2+ sensing proteins can act to transduce change in [Ca2+] to regulate protein function?

Answer 8

• cytoplasmic [Ca2+] maintained at 1x10^-7
• to increase [Ca2+], permeability of plasma membrane and/or ER must increase
• highly regulated process