Visualizing active membrane protein complexes by electron cryotomography
19.06.2014
Gold VA, Ieva R, Walter A, Pfanner N, van der Laan M, Kühlbrandt W.
Nat Commun. 2014 Jun 19;5:4129.
The localization and structural analysis of active membrane protein complexes in their native phospholipid environment is a technically challenging problem. In this article we report on the development of a novel method termed STAMP (Specifically TArgeted Membrane nanoParticle) that allows to label membrane protein complexes in situ with electron-dense quantum dots, which can then be visualized by electron cryotomography. This procedure includes the tagging of a small activating ligand, specific targeting of the tagged ligand to a membrane protein complex and finally attachment of a quantum dot to the ligand-activated molecular machine. We have used this method to study the three-dimensional distribution of preprotein import sites across the surface of mitochondria. Our study revealed that preprotein import sites are not randomly distributed, but preferentially organized into distinct clusters that are often found in proximity to inner membrane crista junctions.
