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Rabbit FKBP59-heat shock protein binding immunophillin (HBI) is a calmodulin binding protein
N Massol1, M C Lebeau, J M Renoir
1Institut National de la Santé et de la Recherche Médicale U 33, Lab. Hormones, Hôpital de Bicêtre, Le Kremlin Bicêtre, France.
Biochemical and Biophysical Research Communications
|September 30, 1992
Summary
Heat shock protein FKBP59-HBI specifically binds Calmodulin (CAM). This interaction, involving identified binding sites and protease susceptibility, suggests a novel regulatory role for this heat shock protein.
Area of Science:
- Molecular Biology
- Protein Biochemistry
Background:
- FKBP59-HBI is a heat shock protein hsp90-binding immunophilin.
- It was initially identified in heterooligomer forms of steroid receptors.
Purpose of the Study:
- To investigate the interaction between FKBP59-HBI and Calmodulin (CAM).
- To identify potential CAM binding sites and functional implications of this interaction.
Main Methods:
- Affinity chromatography using Calmodulin (CAM)-Sepharose 4B with Ca2+ and EGTA.
- Amino acid sequence analysis to identify putative CAM binding sites and PEST sequences.
- In vitro proteolysis using calpain II and antibody-based detection.
Main Results:
- FKBP59-HBI demonstrates specific binding to Calmodulin (CAM) in a calcium-dependent manner.
- The protein sequence contains two putative CAM binding sites and PEST sequences.
- Calpain II proteolysis generates smaller peptides, indicating Ca2+-dependent conformational changes.
Conclusions:
- FKBP59-HBI exhibits a direct and specific interaction with Calmodulin (CAM).
- The identified structural features suggest CAM binding is an intrinsic property of FKBP59-HBI.
- This interaction may play a significant role in the function of this hsp90-binding immunophilin.