This is a seven-bladed beta-propeller, with an N-terminal alpha-helix. Each sheet has 4 beta-strands. The N-terminal beta-strand is part of a sheet with 3 strands from the C-terminus. The sheets are built from the inside out.

Wall, M. A., Coleman, D. E., Lee, E., Iniguez-Lluhi, J. A., Posner, B. A., Gilman, A. G., Sprang, S. R.: The structure of the G protein heterotrimer Gi alpha 1 beta 1 gamma 2. Cell 83 pp. 1047 (1995) (PubMed)

1gg2 (PDB)