SUMMARY PARAGRAPH for KOG1
KOG1 encodes an essential protein that is a component of the TOR complex 1 (TORC1; 2). TORC1 mediates cell growth in response to nutrient availability and cellular stresses by regulating protein synthesis, ribosome biogenesis, autophagy, transcriptional activation, meiosis, cell cycling, nutrient permease sorting and turnover (reviewed in 6, 7). In addition to Kog1p, TORC1 consists of Lst8p, Tco89p and either Tor1p or Tor2p (2, 5). Although TORC1 can contain either Tor1p or Tor2p, Kog1p interacts preferentially with Tor1p (4). TORC1 is sensitive to the drug rapamycin, which forms a complex with Fpr1p that binds to the Tor protein and inhibits complex activity (8, 2). Kog1p depletion mimics rapamycin treatment and cells display the starvation-like phenotypes of cell growth arrest, altered cell morphology, reduction in protein synthesis, glycogen accumulation, and upregulation in the transcription of nitrogen catabolite repressed and retrograde response genes (2).
Kog1p has a molecular weight of 176 kDa and contains four internal HEAT repeats and seven C-terminal WD-40 repeats (2). KOG1 is conserved from yeast to man and is the homolog of the mammalian TOR regulatory protein RAPTOR/mKOG1 (2, 9). TORC1 is also structurally and functionally conserved in higher eukaryotes and has been named the 'nutrient-sensitive complex' in mammals (2, 9). In Drosophila, C. elegans, and mammals, TORC1 activity has been shown to participate in the additional processes of apoptosis, hypoxia, and aging (reviewed in 10, 6).
Last updated: 2005-11-03