These are cryo EM 3D reconstructions of two classes of Ty virus-like particles, with icosahedral T numbers of 3 and 4.
References
AL-Khayat et al (1999) Yeast Ty retrotransposons assemble into
virus-like particles whose T-numbers depend on the C-terminal length
of the capsid protein. J. Mol. Biol. 292, 65-73.
Palmer et al (1997) Cryo-electron
microscopy structure of yeast Ty retrotransposon virus-like particles, J.
Virol.
71, 6863-6868.
Burns et al
(1992) Symmetry, flexibility and permeability in the structure of yeast
retrotransposon virus-like particles,
EMBO J 11, 1155-1164.
Birkbeck Crystallography EM and Image Processing group
Nov 99