title: Estimation of variance in single-particle reconstruction using the bootstrap technique.
abstract: Density maps of a molecule obtained by single-particle reconstruction from thousands of molecule projections exhibit strong changes in local definition and reproducibility, as a consequence of conformational variability of the molecule and non-stoichiometry of ligand binding. These changes complicate the interpretation of density maps in terms of molecular structure. A three-dimensional (3-D) variance map provides an effective tool to assess the structural definition in each volume element. In this work, the different contributions to the 3-D variance in a single-particle reconstruction are discussed, and an effective method for the estimation of the 3-D variance map is proposed, using a bootstrap technique of sampling. Computations with test data confirm the viability, computational efficiency, and accuracy of the method under conditions encountered in practical circumstances.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Texas-Houston Medical School, 6431 Fannin, MSB 6.218, Houston, TX 77030, USA.
authors.forename: Pawel A
authors.initials: PA
authors.lastname: Penczek
authors.forename: Chao
authors.initials: C
authors.lastname: Yang
authors.forename: Joachim
authors.initials: J
authors.lastname: Frank
authors.forename: Christian M T
authors.initials: CM
authors.lastname: Spahn
mesh_terms: D000465:Algorithms; D020285:Cryoelectron Microscopy / Q000379:methods* / Q000706:statistics & numerical data; D005583:Fourier Analysis; D021621:Imaging, Three-Dimensional; D046911:Macromolecular Substances / Q000032:analysis* / Q000737:chemistry; D008968:Molecular Conformation; D009010:Monte Carlo Method
chemical_list: D046911:Macromolecular Substances