Alternative titles; symbols
HGNC Approved Gene Symbol: IPMK
Cytogenetic location: 10q21.1 Genomic coordinates (GRCh38) : 10:58,191,517-58,267,894 (from NCBI)
By searching databases for human sequences similar to yeast Arg82, Nalaskowski et al. (2002) obtained a full-length IPMK cDNA. The deduced 416-amino acid protein has a calculated molecular mass of 47.2 kD. It contains an N-terminal inositol phosphate-binding site, a central ser-ser-leu-leu (SSLL) domain, a basic nuclear localization signal, and a C-terminal ATP-binding site. Fluorescence-tagged human IPMK localized predominantly in the nucleus of transfected rat kidney cells.
By searching for sequences similar to rat Ipmk, Chang et al. (2002) identified human IPMK. Northern blot analysis detected ubiquitous expression of 6- and 4-kb IPMK transcripts, with highest levels in liver, followed by skeletal muscle, placenta, and peripheral blood leukocytes. This pattern of expression differed from that of rat Ipmk, which was highly expressed in kidney and brain.
Nalaskowski et al. (2002) found that recombinant human IPMK phosphorylated inositol 1,4,5-triphosphate (Ins(1,4,5)P3) first to Ins(1,3,4,5)P4, and, upon longer incubation, to Ins(1,3,4,5,6)P5. Ins(1,4,5,6)P4 was also formed at lower levels. No conversion of Ins(1,3,4,5,6)P6 to InsP6 was observed. Under different assay conditions, a small amount of pyrophosphorylated InsP5 was also produced.
Chang et al. (2002) found that recombinant human IPMK preferred Ins(1,3,4,6)P4 over Ins(1,3,4,5)P4 or Ins(1,4,5)P3 as substrate. IPMK was unable to complement loss of its yeast homolog, Ipk2 (Arg82), suggesting that the human and yeast pathways differ.
Nalaskowski et al. (2002) determined that the IPMK gene contains 6 coding exons.
By genomic sequence analysis, Nalaskowski et al. (2002) mapped the IPMK gene to chromosome 10q21.
Chang, S.-C., Miller, A. L., Feng, Y., Wente, S. R., Majerus, P. W. The human homolog of the rat inositol phosphate multikinase is an inositol 1,3,4,6-tetrakisphosphate 5-kinase. J. Biol. Chem. 277: 43836-43843, 2002. [PubMed: 12223481] [Full Text: https://doi.org/10.1074/jbc.M206134200]
Nalaskowski, M. M., Deschermeier, C., Fanick, W., Mayr, G. W. The human homologue of yeast ArgRIII protein is an inositol phosphate multikinase with predominantly nuclear localization. Biochem. J. 366: 549-556, 2002. [PubMed: 12027805] [Full Text: https://doi.org/10.1042/BJ20020327]