Pyro-Technic Control of Metabolism
Robin F. Irvine1, and
Richard M. Denton2
A report by Szijgyarto
et al. on page 802 of this issue (
1) reports some striking evidence for a previously unknown system of intracellular metabolic sensing in eukaryotic cells involving inositol pyrophosphates and reveals some fascinating molecular details of how it may work. The key molecule involved in this potential homeostatic mechanism is an inositol pyrophosphate, inositol 1,2,3,4,6-pentaphosphate 5-pyrophosphate, or IP
7. IP
7 is formed by phosphorylation (strictly, pyrophosphorylation) of the ubiquitous inositol phosphate, IP
6, on the 5-phosphate moiety by a family of kinases, the IP
6 5-kinases (encoded by three genes in mammals; the budding yeast gene is
Kcs1) (
2). It is further pyrophosphorylated in the 1-position to form IP
8 by another family of kinases, the Vip1 family (
3,
4), but the evidence of Szijgyarto
et al. suggests that IP
7 is the key molecule in controlling cellular energeitcs.
1 Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK.
2 School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK.
E-mail: rfi20{at}cam.ac.uk; r.denton{at}bris.ac.uk
