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Sci. STKE, 11 December 2007
Vol. 2007, Issue 416, p. pe72
[DOI: 10.1126/stke.4162007pe72]


A Discrete Signaling Function for an Inositol Pyrophosphate

Philip W. Majerus*

Division of Hematology, Washington University School of Medicine, 660 South Euclid, St. Louis, MO 63110, USA.

Abstract: Inositol pyrophosphates were, until recently, without clearly defined functions. Two recent papers in Science have now clearly defined a function for an IP7 pyrophosphate (inositol hexaphosphate with one pyrophosphate) that is the product of the enzyme encoded by the Vip1 gene in Saccharomyces cerevisiae. This IP7 with a pyrophosphate tentatively assigned to be on either the 4 or 6 position is a cofactor that is required for inactivating the cyclin–cyclin-dependent kinase complex of Pho80, Pho81, and Pho85. Inhibition of the kinase results in the nuclear translocation of Pho4, which is a transcription factor that promotes expression of genes required for phosphate assimilation under conditions of low phosphate. When grown in low-phosphate media, IP7 accumulates, which leads to the expression of genes involved in the acquisition of phosphate.

*Contact information. E-mail, PHIL{at}

Citation: P. W. Majerus, A Discrete Signaling Function for an Inositol Pyrophosphate. Sci. STKE 2007, pe72 (2007).

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