Fold: Retroviral matrix proteins

4-5 helices; right-handed superhelix

Lineage:

1. Root: scop
2. Class: All alpha proteins
3. Fold: Retroviral matrix proteins
   4-5 helices; right-handed superhelix

Superfamilies:

1. Retroviral matrix proteins (4)
   the 5th, C-terminal helix is missing in some of the member structures
   1. Immunodeficiency virus matrix proteins (2)
   2. HTLV-II matrix protein (1)
      the C-terminal helix region is disordered(?)
   3. Mason-pfizer monkey virus matrix protein (1)
      the C-terminal helix region is missing(?)
   4. GAG polyprotein M-domain (1)
      the C-terminal helix region is missing(?)