Targeting of the transcription factor Max during apoptosis: phosphorylation-regulated cleavage by caspase-5 at an unusual glutamic acid residue in position P1

Biochem J. 2001 Sep 15;358(Pt 3):705-15. doi: 10.1042/0264-6021:3580705.


Max is the central component of the Myc/Max/Mad network of transcription factors that regulate growth, differentiation and apoptosis. Whereas the Myc and Mad genes and proteins are highly regulated, Max expression is constitutive and no post-translational regulation is known. We have found that Max is targeted during Fas-induced apoptosis. Max is first dephosphorylated and subsequently cleaved by caspases. Two specific cleavage sites for caspases in Max were identified, one at IEVE(10) decreasing S and one at SAFD(135) decreasing G near the C-terminus, which are cleaved in vitro by caspase-5 and caspase-7 respectively. Mutational analysis indicates that both sites are also used in vivo. Thus Max represents the first caspase-5 substrate. The unusual cleavage after a glutamic acid residue is observed only with full-length, DNA-binding competent Max protein but not with corresponding peptides, suggesting that structural determinants might be important for this activity. Furthermore, cleavage by caspase-5 is inhibited by the protein kinase CK2-mediated phosphorylation of Max at Ser-11, a previously mapped phosphorylation site in vivo. These findings suggest that Fas-mediated dephosphorylation of Max is required for cleavage by caspase-5. The modifications that occur on Max in response to Fas signalling affect the DNA-binding activity of Max/Max homodimers. Taken together, our findings uncover three distinct processes, namely dephosphorylation and cleavage by caspase-5 and caspase-7, that target Max during Fas-mediated apoptosis, suggesting the regulation of the Myc/Max/Mad network through its central component.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Chloromethyl Ketones / pharmacology
  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • Basic-Leucine Zipper Transcription Factors
  • COS Cells
  • Caspase 7
  • Caspases / metabolism*
  • Chlorocebus aethiops
  • Cysteine Proteinase Inhibitors / pharmacology
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • Dimerization
  • Glutamic Acid*
  • Humans
  • Immunoglobulin M / pharmacology
  • Jurkat Cells
  • Mutagenesis, Site-Directed
  • Peptide Fragments / chemistry
  • Peptide Mapping
  • Phosphorylation
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Substrate Specificity
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism
  • Transfection
  • fas Receptor / physiology


  • Amino Acid Chloromethyl Ketones
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • Basic-Leucine Zipper Transcription Factors
  • Cysteine Proteinase Inhibitors
  • DNA-Binding Proteins
  • Immunoglobulin M
  • MAX protein, human
  • Myc associated factor X
  • Peptide Fragments
  • Recombinant Proteins
  • Transcription Factors
  • benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
  • fas Receptor
  • Glutamic Acid
  • CASP5 protein, human
  • CASP7 protein, human
  • Caspase 7
  • Caspases