Turning on a G protein receptor

Abstract

Signal Transduction The mammalian target of rapamycin complex 1 (mTORC1) protein kinase is activated at the lysosomal membrane and helps control autophagy and metabolism. It interacts with other proteins that act as sensors for stimuli like amino acids. Gan et al. used an unbiased screen to discover another protein that functions in this complex, one with similarity to heterotrimeric G protein—coupled receptors (GPCRs). The GPCR-like protein, GPR137B, appears to regulate cycles of association and release of the small guanosine triphosphatase Rag and mTORC1 at the lysosome even in the absence of amino acids. Whether a ligand for the orphan receptor could provide additional regulation adds a further intriguing twist. Nat. Cell Biol. 22 , 614 (2019).