Protein phosphatase 2A on track for nutrient-induced signalling in yeast.
Early studies identified two bona fide protein phosphatase 2A (PP2A)-encoding genes in Saccharomyces cerevisiae, designated PPH21 and PPH22. In addition, three PP2A-related phosphatases, encoded by PPH3, SIT4 and PPG1, have been identified. All share as much as 86% sequence similarity at the amino acid level. This review will focus primarily on Pph21 and Pph22, but some aspects of Sit4 regulation will also be discussed. Whereas a role for PP2A in yeast morphology and cell cycle has been readily recognized, uncovering its function in yeast signal transduction is a more recent breakthrough. Via their interaction with phosphorylated Tap42, PP2A and Sit4 play a pivotal role in target of rapamycin (TOR) signalling. PPH22 overexpression mimics overactive cAMP-PKA (protein kinase A) signalling and PP2A and Sit4 might represent ceramide signalling targets. The methylation of its catalytic subunit stabilizes the heterotrimeric form of PP2A and might counteract TOR signalling. We will show how these new elements could lead us to understand the role and regulation of PP2A in nutrient-induced signalling in baker's yeast.
Zabrocki
Piotr
P
Laboratorium voor Moleculaire Celbiologie, K.U.Leuven, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium.
Van Hoof
Christine
C
Goris
Jozef
J
Thevelein
Johan M
JM
Winderickx
Joris
J
Wera
Stefaan
S
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D003470:Culture Media; D005656:Fungal Proteins / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D054648:Protein Phosphatase 2; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D020123:Sirolimus / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D003470:Culture Media; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C100984:TAP42 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D020123:Sirolimus