RGS-PX1, Gap for Gas and a Sorting Nexin in Vesicular Trafficking
Heterotrimeric GTP–binding proteins (G proteins) control cellular functions by transducing signals from the outside to the inside of cells. Regulator of G protein signaling (RGS) proteins are key modulators of the amplitude and duration of G protein–mediated signaling through their ability to serve as guanosine triphosphatase–activating proteins (GAPs). We have identified RGS-PX1, a Gαs-specific GAP. The RGS domain of RGS-PX1 specifically interacted with Gαs, accelerated its GTP hydrolysis, and attenuated Gαs-mediated signaling. RGS-PX1 also contains a Phox (PX) domain that resembles those in sorting nexin (SNX) proteins. Expression of RGS-PX1 delayed lysosomal degradation of the EGF receptor. Because of its bifunctional role as both a GAP and a SNX, RGS-PX1 may link heterotrimeric G protein signaling and vesicular trafficking.
Bin Zheng, Yong-Chao Ma, Rennolds S Ostrom, Christine Lavoi, Gordon N. Gill, Paul A. Insel, Xin-Yun Huang and Marilyn G. Farquhar. RGS-PX1, GAP for Gas and a sorting nexin in vesicular trafficking. Science, 294:1939-42, 2001.