The phox (phagocyte oxidase) homology (PX) domain occurs in the mammalian phox proteins p40phox and p47phox, the polarity establishment protein Bem1p in budding yeast, and a variety of proteins involved in membrane trafficking. Here we show that the PX domains of p40phox and p47phox directly bind to phosphoinositides: p40phox prefers Ptdlns(3)P, while p47phox does Ptdlns(4)P and Ptdlns(3,4)P2. In addition, the Bem1p PX domain also interacts with Ptdlns(4)P. When the p40phox PX domain is expressed as a fusion to green fluorescent protein in HeLa cells, it exists at early endosomes where Ptdlns(3)P is enriched. Furthermore, a mutant p40phox PX carrying the substitution of Lys for Arg105 only weakly binds to phosphoinositides in vitro, and fails to locate to early endosomes. Thus the PX domain functions as a novel phosphoinositide-binding module and likely participates in targeting of proteins to membranes.
|Number of pages||6|
|Journal||Biochemical and Biophysical Research Communications|
|Publication status||Published - Sept 28 2001|
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology