Sphingoid base signaling via Pkh kinases is required for endocytosis in yeast.
In yeast, sphingoid base synthesis is required for the internalization step of endocytosis and organization of the actin cytoskeleton. We show that overexpression of either one of the two kinases Pkh1p or Pkh2p, that are homologous to mammalian 3-phosphoinositide-dependent kinase-1 (PDK1), can specifically suppress the sphingoid base synthesis requirement for endocytosis. Pkh1p and Pkh2p have an overlapping function because only a mutant with impaired function of both kinases is defective for endocytosis. Pkh1/2p kinases are activated in vitro by nanomolar concentrations of sphingoid base. These results suggest that Pkh1/2p kinases are part of a sphingoid base-mediated signaling pathway that is required for the internalization step of endocytosis. The Pkc1p kinase that is phosphorylated by Pkh1/2p kinases and plays a role in endocytosis was identified as one of the downstream effectors of this signaling cascade.
Friant
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Biozentrum of the University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
Lombardi
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Schmelzle
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Hall
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MN
Riezman
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H
D064413:3-Phosphoinositide-Dependent Protein Kinases; D000199:Actins / Q000235:genetics / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis; D005838:Genotype; D008856:Microscopy, Fluorescence; D009154:Mutation; D010590:Phalloidine / Q000494:pharmacology; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism; D012235:Rhodamines / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D013997:Time Factors
D000199:Actins; D012235:Rhodamines; D029701:Saccharomyces cerevisiae Proteins; D010590:Phalloidine; D011494:Protein Kinases; D064413:3-Phosphoinositide-Dependent Protein Kinases; C118385:PKH1 protein, S cerevisiae; C118386:PKH2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C012491:phytosphingosine; D013110:Sphingosine