Calmodulin

• What is the EF hand.

  A protein motif involved in Ca2+ binding.
• Where are EF hand containing proteins found.

  Cytoplasm.
• Which residues bind Ca2+.

  Aspartate and Glutamate.
• How doe residues bind Ca2+.

  Using the carboxylate oxygen [COO-].
• Why are the alpha helixes amphitatic.

  They contain hydrophobic residues at the core and hydrophillic on the outside.
• What property does glycine cause in the EF hand.

  A sharp bend.
• What does Kd measure.

  Molecular affinity.
• What does Kd stand for.

  Dissociation constant.
• What is the formula for Kd.

  Kd = K2/K1.
• What does K2 stand for.

  Backwords reaction [dissociation].
• What does K1 stand for.

  Forward reaction [Association].
• What is the meaning of Kd.

  The concentration when 50% of the ligand is free and bound.
• What happens to Ca2+ concentration when the cell is stimulated.

  Intracellular Ca2+ increases.
• What does Calmodulin stand for.

  Calcium Modulated Protein.
• What proteins doe Calmodulin activate.

  Kinases.
• Name the 4 main uses of Ca2+.

  1. Secondary messengers for muscular contractions
  2. Hormone and neurotrnasmitter release
  3. Lectin binding to carbohydrates
• What is the basic calmodulin structure. 


  4 EF hands.
• What shape is calmodulin.

  Dumbell.
• What is the name given to the calcium binding.

  Cooperative.
• What is the name of the structure between the EF hands.

  6-turn alpha helices.
• What is APO calmodulin.

  Calmodulin not bound to Ca2+.
• What is APO calmodulin converted to upon Ca2+ binding.

  Calcium-bound calmodulin.
• What happens when calcium binds to calmodulin.

  Conformational change. In which the 6 turn alpha helix is established.
• Describe the conformational change upon calcium binding.

  Calcium binding allows calmodulin to bind to its target protein

  1. 6-turn alpha helix unwinds
  2. Target polypeptide held in hydrophobic channel
• which amino acid allows a central fold in calmodulin

  serine 81