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Regulation of glutamate dehydrogenase by reversible ADP-ribosylation in mitochondria

By Andrés Herrero-Yraola, Siham M.A. Bakhit, Peter Franke, Christoph Weise, Manfred Schweiger, Dierk Jorcke and Mathias Ziegler


Mitochondrial ADP-ribosylation leads to modification of two proteins of ∼26 and 53 kDa. The nature of these proteins and, hence, the physiological consequences of their modification have remained unknown. Here, a 55 kDa protein, glutamate dehydrogenase (GDH), was established as a specific acceptor for enzymatic, cysteine-specific ADP-ribosylation in mitochondria. The modified protein was isolated from the mitochondrial preparation and identified as GDH by N-terminal sequencing and mass spectrometric analyses of tryptic digests. Incubation of human hepatoma cells with [14C]adenine demonstrated the occurrence of the modification in vivo. Purified GDH was ADP-ribosylated in a cysteine residue in the presence of the mitochondrial activity that transferred the ADP-ribose from NAD+ onto the acceptor site. ADP- ribosylation of GDH led to substantial inhibition of its catalytic activity. The stoichiometry between incorporated ADP-ribose and GDH subunits suggests that modification of one subunit per catalytically active homohexamer causes the inactivation of the enzyme. Isolated, ADP-ribosylated GDH was reactivated by an Mg2+-dependent mitochondrial ADP-ribosylcysteine hydrolase. GDH, a highly regulated enzyme, is the first mitochondrial protein identified whose activity may be modulated by ADP-ribosylation

Topics: Article
Publisher: Oxford University Press
Year: 2001
DOI identifier: 10.1093/emboj
OAI identifier:
Provided by: PubMed Central
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