Paramagnetic Relaxation Enhancement Reveals Oligomerization Interface of a Membrane Protein

다국어 초록 (Multilingual Abstract)

<P>Protein–protein interactions play critical roles in cellular function and oligomerization of membrane proteins is a commonly observed phenomenon. Determining the oligomerization state and defining the intermolecular interface in the bilayer is generally a difficult task. Here, we use site-specific spin labeling to demonstrate that relaxation enhancements induced by covalently attached paramagnetic tag can provide distance restraints defining the intermonomer interface in oligomers formed by a seven-helical transmembrane protein <I>Anabaena</I> Sensory Rhodopsin (ASR). We combine these measurements with visible CD spectroscopy and cross-linking experiments to demonstrate that ASR forms tight trimers in both detergents and lipids.</P><P><B>Graphic Abstract</B>
<IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-41/ja308310z/production/images/medium/ja-2012-08310z_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja308310z'>ACS Electronic Supporting Info</A></P>