ELECTRON TOMOGRAPHY OF SINGLE ICE-EMBEDDED MACROMOLECULES - 3-DIMENSIONAL ALIGNMENT AND CLASSIFICATION

From 3-D reconstructions of automatically recorded tilt series of ice- embedded macromolecules, several hundred 3-D images of single particle s can be extracted. Here we describe correlation-based techniques to a lign the particles with respect to translation and orientation in 3-D and the calculation of an averaged reconstruction after application of the correct weighting function to the particle projections. Multivari ate statistical analysis and classification are applied to the set of three-dimensionally reconstructed particles to investigate interimage variations on the 3-D level. (C) 1997 Academic Press.