title: Identification of macromolecular complexes in cryoelectron tomograms of phantom cells.
abstract: Electron tomograms of intact frozen-hydrated cells are essentially three-dimensional images of the entire proteome of the cell, and they depict the whole network of macromolecular interactions. However, this information is not easily accessible because of the poor signal-to-noise ratio of the tomograms and the crowded nature of the cytoplasm. Here, we describe a template matching algorithm that is capable of detecting and identifying macromolecules in tomographic volumes in a fully automated manner. The algorithm is based on nonlinear cross correlation and incorporates elements of multivariate statistical analysis. Phantom cells, i.e., lipid vesicles filled with macromolecules, provide a realistic experimental scenario for an assessment of the fidelity of this approach. At the current resolution of approximately 4 nm, macromolecules in the size range of 0.5-1 MDa can be identified with good fidelity.
authors.affiliation: Max-Planck-Institut für Biochemie, Molekulare Strukturbiologie, Am Klopferspitz 18a, 82152 Martinsried, Germany. frangak@biochem.mpg.de
authors.forename: Achilleas S
authors.initials: AS
authors.lastname: Frangakis
authors.forename: Jochen
authors.initials: J
authors.lastname: Böhm
authors.forename: Friedrich
authors.initials: F
authors.lastname: Förster
authors.forename: Stephan
authors.initials: S
authors.lastname: Nickell
authors.forename: Daniela
authors.initials: D
authors.lastname: Nicastro
authors.forename: Dieter
authors.initials: D
authors.lastname: Typke
authors.forename: Reiner
authors.initials: R
authors.lastname: Hegerl
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumeister
mesh_terms: D000465:Algorithms; D019843:Archaeal Proteins / Q000032:analysis*; D018833:Chaperonins / Q000032:analysis*; D018699:Coated Vesicles; D020285:Cryoelectron Microscopy / Q000379:methods; D003546:Cysteine Endopeptidases / Q000032:analysis*; D008081:Liposomes / Q000737:chemistry; D009097:Multienzyme Complexes / Q000032:analysis*; D015999:Multivariate Analysis; D017711:Nonlinear Dynamics; D046988:Proteasome Endopeptidase Complex
chemical_list: D019843:Archaeal Proteins; D008081:Liposomes; D009097:Multienzyme Complexes; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D018833:Chaperonins