The Skap-hom dimerization and PH domains comprise a 3'-phosphoinositide-gated molecular switch

Mol Cell. 2008 Nov 21;32(4):564-75. doi: 10.1016/j.molcel.2008.09.022.


PH domains, by binding to phosphoinositides, often serve as membrane-targeting modules. Using crystallographic, biochemical, and cell biological approaches, we have uncovered a mechanism that the integrin-signaling adaptor Skap-hom uses to mediate cytoskeletal interactions. Skap-hom is a homodimer containing an N-terminal four-helix bundle dimerization domain, against which its two PH domains pack in a conformation incompatible with phosphoinositide binding. The isolated PH domains bind PI[3,4,5]P(3), and mutations targeting the dimerization domain or the PH domain's PI[3,4,5]P(3)-binding pocket prevent Skap-hom localization to ruffles. Targeting is retained when the PH domain is deleted or by combined mutation of the PI[3,4,5]P(3)-binding pocket and the PH/dimerization domain interface. Thus, the dimerization and PH domain form a PI[3,4,5]P(3)-responsive molecular switch that controls Skap-hom function.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / chemistry*
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Amino Acid Sequence
  • Animals
  • Dimerization
  • Green Fluorescent Proteins / metabolism
  • Mice
  • Mice, Knockout
  • Models, Chemical
  • Models, Molecular
  • Molecular Sequence Data
  • Phosphatidylinositols / chemistry*
  • Phosphatidylinositols / genetics
  • Phosphatidylinositols / metabolism*
  • Point Mutation
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Retroviridae / genetics
  • Sequence Homology, Amino Acid
  • Transduction, Genetic


  • Adaptor Proteins, Signal Transducing
  • Phosphatidylinositols
  • Green Fluorescent Proteins

Associated data

  • PDB/1U5G
  • PDB/2OTX

Grant support