MAP kinases Erk1/2 phosphorylate sterol regulatory element-binding protein (SREBP)-1a at serine 117 in vitro.
Sterol regulatory element-binding protein (SREBP)-1a is a transcription factor sensing cellular cholesterol levels and integrating gene regulatory signals mediated by MAP kinase cascades. Here we report the identification of serine 117 in SREBP-1a as the major phosphorylation site of the MAP kinases Erk1/2. This site was identified by nanoelectrospray mass spectrometry and peptide sequencing of recombinant fusion proteins phosphorylated by Erk1/2 in vitro. Serine 117 was verified as the major phosphorylation site by in vitro mutagenesis. Mutation of serine 117 to alanine abolished Erk2-mediated phosphorylation in vitro and the MAP kinase-related transcriptional activation of SREBP-1a by insulin and platelet-derived growth factor in vivo. Our data indicate that the MAP kinase-mediated effects on SREBP-1a-regulated target genes are linked to this phosphorylation site.
Klinik II und Poliklinik für Innere Medizin am Zentrum für Molekulare Medizin der Universität zu Köln and Proteinstrukturlabor der Ruhr-Universität Bochum, 50924 Cologne, Germany.
G
G
Roth
J
J
Kotzka
L
L
Kremer
S
S
Lehr
C
C
Lohaus
H E
HE
Meyer
W
W
Krone
D
D
Müller-Wieland
D000595:Amino Acid Sequence; D022762:CCAAT-Enhancer-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011973:Receptors, LDL / Q000235:genetics; D012694:Serine / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D007328:Insulin; D010982:Platelet-Derived Growth Factor; D011973:Receptors, LDL; C497387:SREBF1 protein, human; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; D012694:Serine; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases