The isocitrate dehydrogenase phosphorylation cycle: Regulation and enzymology

David C. Laporte

Research output: Contribution to journalArticlepeer-review

72 Scopus citations


Isocitrate dehydrogenase (IDH) of Escherichia coli is regulated by phosphorylation and dephosphorylation. This phosphorylation cycle controls the flow of isocitrate through the glyoxylate bypass, a pathway which bypasses the CO2 evolving steps of the Krebs' cycle. IDH is phosphorylated at a single serine which resides in its active site. Phosphorylation blocks isocitrate binding, thereby inactivating IDH. The IDH phosphorylation cycle is catalyzed by a bifunctional protein kinase/phosphatase. The kinase and phosphatase reactions appear to be catalyzed at the same site and may share some catalytic steps. A variety of approaches have been used to examine the IDH phosphorylation cycle in the intact organism. The picture which has emerged is one of an exquisitely sensitive and flexible system which is capable of adapting efficiently to the environment both inside and outside the cell. © 1993 Wiley‐Liss, Inc.

Original languageEnglish (US)
Pages (from-to)14-18
Number of pages5
JournalJournal of Cellular Biochemistry
Issue number1
StatePublished - Jan 1993
Externally publishedYes


  • Krebs' cycle
  • dephosphorylation
  • glyoxylate bypass
  • isocitrate
  • phosphorylation


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