The function of the transcription regulator ArgRIII in the expression of several genes involved in the metabolism of arginine in yeast has been well studied. It was previously reported that it is also an inositol phosphate multikinase and an important factor of the mRNA export pathway [reviewed by Shears (2000) Bioessays 22, 786–789]. In the present study we report the cloning of a full-length 1248-bp cDNA encoding a human inositol phosphate multikinase (IPMK). This protein has a calculated molecular mass of 47.219kDa. Functionally important motifs [inositol phosphate-binding site, ATP-binding site, catalytically important SSLL (Ser-Ser-Leu-Leu) domain] are conserved between the human IPMK and yeast ArgRIII. Bacterially expressed protein demonstrated an inositol phosphate multikinase activity similar to that of yeast ArgRIII. Ins(1,4,5)P3 is phosphorylated at positions 3 and 6 up to Ins(1,3,4,5,6)P5. The human IPMK fused with a fluorescent protein tag is localized predominantly in the nucleus when transiently expressed in mammalian cells. A basic cluster in the protein's C-terminus is positively involved in nuclear targeting. These findings are consistent with the concept of a nuclear inositol phosphate signalling and phosphorylation pathway in mammalian cells.
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September 2002
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Research Article|
September 01 2002
The human homologue of yeast ArgRIII protein is an inositol phosphate multikinase with predominantly nuclear localization
Marcus M. NALASKOWSKI;
Marcus M. NALASKOWSKI
Universitaetsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie, Abteilung für Zellulaere Signaltransduktion, Martinistrasse 52, 20246 Hamburg, Germany
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Christina DESCHERMEIER;
Christina DESCHERMEIER
Universitaetsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie, Abteilung für Zellulaere Signaltransduktion, Martinistrasse 52, 20246 Hamburg, Germany
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Werner FANICK;
Werner FANICK
Universitaetsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie, Abteilung für Zellulaere Signaltransduktion, Martinistrasse 52, 20246 Hamburg, Germany
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Georg W. MAYR
Georg W. MAYR
1
Universitaetsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie, Abteilung für Zellulaere Signaltransduktion, Martinistrasse 52, 20246 Hamburg, Germany
1To whom correspondence should be addressed (e-mail mayr@uke.uni-hamburg.de).
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Publisher: Portland Press Ltd
Received:
February 25 2002
Revision Received:
May 23 2002
Accepted:
May 23 2002
Accepted Manuscript online:
May 31 2002
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2002
2002
Biochem J (2002) 366 (2): 549–556.
Article history
Received:
February 25 2002
Revision Received:
May 23 2002
Accepted:
May 23 2002
Accepted Manuscript online:
May 31 2002
Citation
Marcus M. NALASKOWSKI, Christina DESCHERMEIER, Werner FANICK, Georg W. MAYR; The human homologue of yeast ArgRIII protein is an inositol phosphate multikinase with predominantly nuclear localization. Biochem J 1 September 2002; 366 (2): 549–556. doi: https://doi.org/10.1042/bj20020327
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