Hu M C, Tang-Oxley Q, Qiu W R, Wang Y P, Mihindukulasuriya K A, Afshar R, Tan T H
Department of Cell Biology, Amgen, Inc., Thousand Oaks, California 91320, USA.
J Biol Chem. 1998 Dec 11;273(50):33561-5. doi: 10.1074/jbc.273.50.33561.
Nuclear factor kappaB (NF-kappaB) and the Rel family of proteins are pleiotropic transcription factors that play central roles in the immune and inflammatory responses, as well as apoptosis. Here, we identified a serine/threonine protein phosphatase X (PPX; also called protein phosphatase 4 (PP4)) that specifically associated with c-Rel, NF-kappaB p50, and RelA. The amino acid sequences of human and mouse PPX are 100% identical, and the PPX gene was mapped to human chromosome 16 p11.2. Overexpression of PPX, but not catalytically inactive PPX mutants, stimulated the DNA-binding activity of c-Rel and activated NF-kappaB-mediated transcription. These results suggest that PPX is a novel activator of c-Rel/NF-kappaB.
