Related Experiment Videos
The C-terminus and the Ca2+ low-affinity binding sites in bacteriorhodopsin
1Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.
Biochemistry
|December 28, 1993
Summary
Bacteriorhodopsin (bR) has low-affinity calcium binding sites. Removing the C-terminus eliminates most of these sites, indicating they are located on the protein's surface.
Area of Science:
- Biochemistry
- Biophysics
- Membrane Proteins
Background:
- Bacteriorhodopsin (bR) possesses known high-affinity Ca2+ binding sites within its structure.
- Previous research localized these high-affinity sites near the retinal pocket using site-directed mutagenesis.
Purpose of the Study:
- To investigate the location of the four to six low-affinity Ca2+ binding sites in bacteriorhodopsin.
- To determine if the C-terminus of bacteriorhodopsin is involved in these low-affinity binding sites.
Main Methods:
- Studied Ca2+ binding to deionized bacteriorhodopsin and a C-terminus-truncated variant.
- Employed potentiometric titration with Ca2+-selective electrodes.
- Analyzed titration data using Scatchard plots.
Main Results:
- Removal of the C-terminus significantly reduced the number of low-affinity Ca2+ binding sites in bacteriorhodopsin.
- The results indicate that the majority of low-affinity Ca2+ binding sites are located on the surface of bacteriorhodopsin.
Conclusions:
- The C-terminus of bacteriorhodopsin plays a crucial role in the formation or accessibility of its surface-located low-affinity Ca2+ binding sites.
- Further investigation into the specific involvement of the C-terminus is warranted.