Journal
BIOCHEMISTRY
Volume 41, Issue 4, Pages 1123-1128Publisher
AMER CHEMICAL SOC
DOI: 10.1021/bi015828s
Keywords
-
Categories
Funding
- NIGMS NIH HHS [GM58568, R01 GM058568] Funding Source: Medline
Ask authors/readers for more resources
This study presents an approach to identifying surface residues on membrane proteins that are exposed toward the membrane-aqueous interface. The method employs a lipid Ni(II) chelate that localizes the metal ion to a region near the membrane-aqueous interface. Lateral diffusion of the lipid chelate results in Heisenberg exchange (HE) with nitroxide side chains in the protein only if direct contact occurs between the paramagnetic species during a collision. Thus, HE serves as a signature for residues facing the bilayer in the neighborhood of the membrane-aqueous interface. To evaluate the method, 13 surface residues on the extracellular half of KcsA, a prokaryotic potassium channel of known structure, were examined for HE with the Ni(II) chelate. The HE rate between the two species is found to depend strongly on the vertical position of the nitroxide with respect to the membrane-aqueous interface. Nitroxides introduced near the interface experience relatively high HE rates, whereas nitroxides that are immersed in the bilayer interior or sterically sheltered from collision experience low or undetectable rates. The results indicate that residues near the interface. can be identified on the basis of their high rates of collision with the headgroup region of the bilayer.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available