title: Tetartohedral twinning could happen to you too.
abstract: Tetartohedral crystal twinning is discussed as a particular case of (pseudo)merohedral twinning when the number of twinned domains is four. Tetartohedrally twinned crystals often possess pseudosymmetry, with the rotational part of the pseudosymmetry operators coinciding with the twinning operators. Tetartohedrally twinned structures from the literature are reviewed and the recent structure determination of tetartohedrally twinned triclinic crystals of human complement factor I is discussed.
authors.affiliation: Sir William Dunn School of Pathology, Oxford University, South Parks Road, Oxford OX1 3RE, England. pietro.roversi@path.ox.ac.uk
authors.forename: Pietro
authors.initials: P
authors.lastname: Roversi
authors.forename: Eric
authors.initials: E
authors.lastname: Blanc
authors.forename: Steven
authors.initials: S
authors.lastname: Johnson
authors.forename: Susan Mary
authors.initials: SM
authors.lastname: Lea
mesh_terms: D017244:Complement Factor I / Q000032:analysis / Q000737:chemistry; D018360:Crystallography, X-Ray / Q000379:methods*; D030562:Databases, Protein; D006801:Humans
chemical_list: C493611:CFI protein, human; D017244:Complement Factor I