Calmodulin binding to the polybasic C-termini of STIM proteins involved in store-operated calcium entry.
Translocation of STIM1 and STIM2 from the endoplasmic reticulum to the plasma membrane is a key step in store-operated calcium entry in the cell. We show by isothermal titration calorimetry that calmodulin binds in a calcium-dependent manner to the polybasic C-termini of STIM1 and STIM2, a region critical for their translocation to the plasma membrane ( K D < or = 1 microM in calcium). HSQC NMR spectroscopy shows this interaction is in the fast exchange regime. By binding STIM1 and STIM2, calmodulin may regulate store refilling, thereby ensuring the maintenance of its own action in intracellular signaling.
Bauer
Mikael C
MC
Lund University, Biophysical Chemistry, Chemical Centre, P O Box 124, SE221 00 Lund, Sweden.
O'Connell
David
D
Cahill
Dolores J
DJ
Linse
Sara
S
D001665:Binding Sites; D002118:Calcium / Q000502:physiology*; D002147:Calmodulin / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000502:physiology*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000737:chemistry / Q000378:metabolism*; D009587:Nitrogen Isotopes; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D000071737:Stromal Interaction Molecule 1; D000071738:Stromal Interaction Molecule 2
D002147:Calmodulin; D015815:Cell Adhesion Molecules; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D009587:Nitrogen Isotopes; D010446:Peptide Fragments; C103530:STIM1 protein, human; C513279:STIM2 protein, human; D000071737:Stromal Interaction Molecule 1; D000071738:Stromal Interaction Molecule 2; D002118:Calcium