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Interaction of calponin with phospholipids
1Department of Functional Polymer Science, Faculty of Textile Science and Technology, Shinshu University, Nagano.
Journal of Biochemistry
|May 1, 1995
Summary
Chicken gizzard calponin binds to phosphatidylserine (PS) and phosphatidylinositol (PI) vesicles, but not phosphatidylcholine (PC). This binding occurs in the N-terminal fragment and is influenced by ionic strength, Ca2+, and Mg2+.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Calponin is a protein found in smooth muscle.
- Its interaction with phospholipids is not well understood.
Purpose of the Study:
- To investigate the interaction between chicken gizzard calponin and various phospholipids.
- To identify the binding site and factors affecting this interaction.
Main Methods:
- Sedimentation assay
- Affinity chromatography
- Chymotryptic digestion
- Domain mapping
Main Results:
- Calponin binds to phosphatidylserine (PS) and phosphatidylinositol (PI) vesicles, with apparent Kd values of 1.3 x 10^6 M^-1 and 1.5 x 10^6 M^-1, respectively.
- The N-terminal 22-kDa fragment of calponin contains the phospholipid-binding site.
- Binding is sensitive to ionic strength, Ca2+ concentration, and requires MgCl2 for PS interaction.
- Actin, calmodulin, and S100 inhibit binding, with calmodulin and S100 inhibition dependent on CaCl2.
Conclusions:
- Chicken gizzard calponin interacts specifically with acidic phospholipids (PS and PI).
- The N-terminal domain is crucial for phospholipid binding.
- Protein-protein interactions and ionic conditions modulate calponin-phospholipid binding.