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Characterization of the binding sites for the interactions between FKBP12 and intracellular calcium release channels

He Wen1, Sunmi Kang, Youngmin Song

  • 1Department of Biochemistry, College of Medicine, Inha University, Shinheung-dong, Chung-gu, Incheon, Republic of Korea.

Archives of Biochemistry and Biophysics
|November 22, 2011
PubMed

Insights

FKBP12 protein binds to calcium channels RyR1, RyR3, and IP(3)R1. The drug FK506 competitively inhibits this interaction, clarifying the binding mechanism.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Calcium Signaling

Background:

  • FKBP12 protein is known to interact with type 1 ryanodine receptors (RyR1).
  • Controversy exists regarding FKBP12's interaction with other calcium channels like IP(3)R1 and RyR3.
  • The role of prolyl-dipeptide motifs and specific binding residues in these interactions is debated.

Purpose of the Study:

  • To biochemically confirm the interaction of FKBP12 with RyR1, RyR3, and IP(3)R1.
  • To identify the specific binding residues of FKBP12 involved in these interactions.
  • To elucidate the role of the FK506 drug in modulating these protein-channel interactions.

Main Methods:

  • Pulldown assays using recombinant proteins to test interactions.
  • Nuclear Magnetic Resonance (NMR) chemical shift mapping to pinpoint binding sites.
  • Competitive inhibition assays using FK506.

Main Results:

  • Biochemical evidence confirmed FKBP12 interacts with RyR1, RyR3, and IP(3)R1.
  • NMR mapping identified key FKBP12 binding residues within its FK506 binding region.
  • FK506 was shown to competitively inhibit FKBP12 binding to the dipeptide motifs of the calcium channels.

Conclusions:

  • FKBP12 directly interacts with RyR1, RyR3, and IP(3)R1.
  • The hydrophobic FK506 binding region of FKBP12 is crucial for channel interaction.
  • FK506 serves as a competitive inhibitor, offering insights into the binding mechanism.

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