Related Experiment Videos
Inositol polyphosphate multikinase (ArgRIII) determines nuclear mRNA export in Saccharomyces cerevisiae
A Saiardi1, J J Caffrey, S H Snyder
1Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Abstract:
The ARGRIII gene of Saccharomyces cerevisiae encodes a transcriptional regulator that also has inositol polyphosphate multikinase (ipmk) activity [Saiardi et al. (1999) Curr. Biol. 9, 1323-1326]. To investigate how inositol phosphates regulate gene expression, we disrupted the ARGRIII gene. This mutation impaired nuclear mRNA export, slowed cell growth, increased cellular [InsP(3)] 170-fold and decreased [InsP(6)] 100-fold, indicating reduced phosphorylation of InsP(3) to InsP(6). Levels of diphosphoinositol polyphosphates were decreased much less dramatically than was InsP(6). Low levels of InsP(6), and considerable quantities of Ins(1,3,4,5)P(4), were synthesized by an ipmk-independent route. Transcriptional control by ipmk reflects that it is a pivotal regulator of nuclear mRNA export via inositol phosphate metabolism.