Abstract

Polydispersity, heterogeneity and insolubility are among the most challenging properties of protein complexes making them almost impossible to study by conventional structural biology approaches. Building on our early experiments of intact ribosomes we have recently explored the subunit architecture of the eukaryotic initiation factor 3 (eIF3) and the role of post translational modifications in ribosomal proteins and their complexes. Our recent discoveries that large integral membrane protein complexes can survive intact in the mass spectrometer (Barrera, Di Bartolo et al. 2008; Barrera, Isaacson et al. 2009) allow us to apply mass spectrometry methods to some of the most challenging and controversial membrane protein complexes studied to date. Specifically I will describe how the lipid binding properties within these protein complexes is enabling us to shed new light on their structure and function. I will also describe how ion mobility measurements are constraining molecular models of membrane subunits within the intact ensemble of structures. References

Barrera, N. P., N. Di Bartolo, et al. (2008). “Micelles protect membrane complexes from solution to vacuum.” Science 321(5886): 243-246. Barrera, N. P., S. C. Isaacson, et al. (2009). “Mass spectrometry of membrane transporters reveals subunit stoichiometry and interactions.” Nature Methods 6(8): 585-587.