8 Tor-signaling and Tor-interacting proteins in yeast

Abstract

The Tor (target of rapamycin) signaling pathway is an important mechanism used by eukaryotic cells to regulate their growth in response to nutrient-related environmental cues. Recent studies have revealed that the two Tor kinases in S. cerevisiae, Tor1p and Tor2p, regulate gene expression at several levels, including transcription, translation, intracellular protein trafficking, as well as protein stability. How the activity of each kinase is controlled remains to be elucidated, however, as does the nature of potential upstream regulatory signals. Here we review recent efforts to address these issues by focusing on two areas related to Tor signaling: (1) transcriptional control of genes required for the de novo biosynthesis of glutamate and glutamine and (2) characterization of interacting partners of Tor1p and Tor2p. These studies have converged in unanticipated ways to yield new insights into how these kinases may function both to receive as well as transmit nutritional information in yeast.