Structural basis for dimerization of the Dictyostelium gelation factor (ABP120) rod

Nat Struct Biol. 1999 Sep;6(9):836-41. doi: 10.1038/12296.


Gelation factor (ABP120) is one of the principal actin-cross-linking proteins of Dictyostelium discoideum. The extended molecule has an N-terminal 250-residue actin-binding domain and a rod constructed from six 100-residue repeats that have an Ig fold. The ability to dimerize is crucial to the actin cross-linking function of gelation factor and is mediated by the rod in which the two chains are arranged in an antiparallel fashion. We report the 2.2 A resolution crystal structure of rod domains 5 and 6, which shows that dimerization is mediated primarily by rod domain 6 and is the result of a double edge-to-edge extension of beta-sheets. Thus, contrary to earlier proposals, the chains of the dimeric gelation factor molecule overlap only within domain 6, and domains 1-5 do not pair with domains from the other chain. This information allows construction of a model of the gelation factor molecule and suggests how the chains in the related molecule filamin (ABP280) may interact.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Carrier Proteins / chemistry*
  • Carrier Proteins / metabolism*
  • Contractile Proteins / chemistry
  • Contractile Proteins / metabolism
  • Crystallization
  • Crystallography, X-Ray
  • Dictyostelium / chemistry*
  • Dimerization
  • Electrons
  • Filamins
  • Microfilament Proteins / chemistry*
  • Microfilament Proteins / metabolism*
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Structure, Secondary
  • Sequence Alignment


  • Carrier Proteins
  • Contractile Proteins
  • Filamins
  • Microfilament Proteins
  • abpC protein, Dictyostelium

Associated data

  • PDB/1QFH