title: Electron microscopic study of crystals of the Xenopus laevis transcription factor IIIA-5S ribosomal RNA complex.
abstract: A novel method has been developed to grow crystals of the Xenopus laevis transcription factor IIIA-5S RNA complex directly on grids for examination by electron microscopy. Microcrystals were examined in negative stain and in thin sections to reveal a hexagonal lattice with unit-cell dimensions a = b = 87.1 +/- 4.4 A and c = 143.8 +/- 12.7 A. Optical diffraction patterns from micrographs were obtained about the major crystal axes extending to about 40-A resolution. A packing scheme is proposed for which there are three or six transcription factor IIIA-5S RNA complexes in the unit cell related by 3(1) symmetry along the long cell axis. This would require that the 5S RNA molecules are arranged end-to-end, with the terminal loops of adjacent molecules overlapping.
authors: European Molecular Biology Laboratory, Heidelberg, Federal Republic of Germany.
authors: R S
authors: RS
authors: Brown
authors: C
authors: C
authors: Ferguson
authors: A
authors: A
authors: Kingswell
authors: F K
authors: FK
authors: Winkler
authors: K R
authors: KR
authors: Leonard
mesh_terms: D000818:Animals; D003461:Crystallography; D004268:DNA-Binding Proteins; D008854:Microscopy, Electron; D012335:RNA, Ribosomal; D012341:RNA, Ribosomal, 5S; D014157:Transcription Factors; D014982:Xenopus laevis
chemical_list: D004268:DNA-Binding Proteins; D012335:RNA, Ribosomal; D012341:RNA, Ribosomal, 5S; D014157:Transcription Factors