Crystal structure of the ARF-GAP domain and ankyrin repeats of PYK2-associated protein beta

EMBO J. 1999 Dec 15;18(24):6890-8. doi: 10.1093/emboj/18.24.6890.


ADP ribosylation factors (ARFs), which are members of the Ras superfamily of GTP-binding proteins, are critical components of vesicular trafficking pathways in eukaryotes. Like Ras, ARFs are active in their GTP-bound form, and their duration of activity is controlled by GTPase-activating proteins (GAPs), which assist ARFs in hydrolyzing GTP to GDP. PAPbeta, a protein that binds to and is phosphorylated by the non-receptor tyrosine kinase PYK2, contains several modular signaling domains including a pleckstrin homology domain, an SH3 domain, ankyrin repeats and an ARF-GAP domain. Sequences of ARF-GAP domains show no recognizable similarity to those of other GAPs, and contain a characteristic Cys-X(2)-Cys-X(16-17)-Cys-X(2)-Cys motif. The crystal structure of the PAPbeta ARF-GAP domain and the C-terminal ankyrin repeats has been determined at 2.1 A resolution. The ARF-GAP domain comprises a central three-stranded beta-sheet flanked by five alpha-helices, with a Zn(2+) ion coordinated by the four cysteines of the cysteine-rich motif. Four ankyrin repeats are also present, the first two of which form an extensive interface with the ARF-GAP domain. An invariant arginine and several nearby hydrophobic residues are solvent exposed and are predicted to be the site of interaction with ARFs. Site-directed mutagenesis of these residues confirms their importance in ARF-GAP activity.

Publication types

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

MeSH terms

  • ADP-Ribosylation Factors / chemistry*
  • ADP-Ribosylation Factors / metabolism
  • Amino Acid Sequence
  • Ankyrins / chemistry*
  • Ankyrins / metabolism
  • Catalysis
  • Computer Graphics
  • Crystallography, X-Ray / methods
  • Focal Adhesion Kinase 2
  • Kinetics
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Protein Structure, Secondary
  • Protein-Tyrosine Kinases / chemistry*
  • Protein-Tyrosine Kinases / metabolism*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Repetitive Sequences, Amino Acid
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • src Homology Domains


  • Ankyrins
  • Recombinant Proteins
  • Protein-Tyrosine Kinases
  • Focal Adhesion Kinase 2
  • ADP-Ribosylation Factors

Associated data

  • PDB/1DCQ